{"id":1658,"date":"2019-08-08T13:42:31","date_gmt":"2019-08-08T17:42:31","guid":{"rendered":"https:\/\/pressbooks.bccampus.ca\/dcbiol110311092nded\/chapter\/unit-13-joints\/"},"modified":"2023-10-23T01:39:41","modified_gmt":"2023-10-23T05:39:41","slug":"unit-13-joints","status":"publish","type":"chapter","link":"https:\/\/pressbooks.bccampus.ca\/dcbiol110311092nded\/chapter\/unit-13-joints\/","title":{"raw":"Unit 13: Joints","rendered":"Unit 13: Joints"},"content":{"raw":"<div class=\"unit-13:-joints\">\r\n<div class=\"textbox shaded\">\r\n\r\n<strong>Unit outline<\/strong>\r\n\r\n<strong>Joints<\/strong>\r\n\r\n<a href=\"#13-1\"><strong>Part 1:<\/strong> Overview and Classification of Joints<\/a>\r\n<ul>\r\n \t<li><a href=\"#13-1a\">Structural classification<\/a><\/li>\r\n \t<li><a href=\"#13-1b\">Functional classification<\/a><\/li>\r\n<\/ul>\r\n<a href=\"#13-2\"><strong>Part 2: <\/strong>Fibrous Joints<\/a>\r\n<ul>\r\n \t<li><a href=\"#13-2a\">Suture<\/a><\/li>\r\n \t<li><a href=\"#13-2b\">Syndesmosis<\/a><\/li>\r\n \t<li><a href=\"#13-2c\">Gomphosis<\/a><\/li>\r\n<\/ul>\r\n<a href=\"#13-3\"><strong>Part 3:<\/strong> Cartilaginous Joints<\/a>\r\n<ul>\r\n \t<li><a href=\"#13-3a\">Synchondrosis<\/a><\/li>\r\n \t<li><a href=\"#13-3b\">Symphysis<\/a><\/li>\r\n<\/ul>\r\n<a href=\"#13-4\"><strong>Part 4:<\/strong> Synovial Joints<\/a>\r\n<ul>\r\n \t<li><a href=\"#13-4a\">Structural features of synovial joints<\/a><\/li>\r\n \t<li><a href=\"#13-4b\">Additional structures associated with synovial joints<\/a><\/li>\r\n \t<li><a href=\"#13-4c\">Types of synovial joints<\/a><\/li>\r\n<\/ul>\r\n<h2><a href=\"#P\">Practice Questions<\/a><\/h2>\r\n<\/div>\r\n<div class=\"textbox textbox--learning-objectives\"><header class=\"textbox__header\">\r\n<p class=\"textbox__title\"><strong>Learning Objectives<\/strong><\/p>\r\n\r\n<\/header>\r\n<div class=\"textbox__content\">\r\n\r\nAt the end of this unit, you should be able to:\r\n<p class=\"hanging-indent\"><strong>I.<\/strong> Explain what is meant by the terms synarthrotic, diarthrotic, and amphiarthrotic as descriptions of the functional classes of joints.<\/p>\r\n<p class=\"hanging-indent\"><strong>II. <\/strong>Describe the structures, classifications, functions, and locations of the various types of joints in the human body.<\/p>\r\n<p class=\"hanging-indent\"><strong>III. <\/strong>Describe the structure of a synovial joint and using the knee joint as an example, specify the functions of each component.<\/p>\r\n<p class=\"hanging-indent\"><strong>IV.<\/strong> Describe the movements allowed by synovial joints and specify examples of each.<\/p>\r\n<p class=\"hanging-indent\"><strong>V.<\/strong> Describe the structures and movements allowed by each type of synovial joint and also specify an example of each in the human body.<\/p>\r\n\r\n<\/div>\r\n<\/div>\r\n<div class=\"textbox textbox--learning-objectives\"><header class=\"textbox__header\">\r\n<p class=\"textbox__title\"><strong>Learning Objectives and Guiding Questions<\/strong><\/p>\r\n\r\n<\/header>\r\n<div class=\"textbox__content\">\r\n\r\nAt the end of this unit, you should be able to complete all the following tasks, including answering the guiding questions associated with each task.\r\n<p class=\"hanging-indent\"><strong>I.<\/strong> Explain what is meant by the terms synarthrotic, diarthrotic, and amphiarthrotic as descriptions of the functional classes of joints.<\/p>\r\n\r\n<ol>\r\n \t<li class=\"hanging-indent\">Define each of the following terms:\r\n<ul>\r\n \t<li class=\"hanging-indent\">Synarthrotic joint<\/li>\r\n \t<li class=\"hanging-indent\">Diarthrotic joint<\/li>\r\n \t<li class=\"hanging-indent\">Amphiarthrotic joint<\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ol>\r\n<p class=\"hanging-indent\"><strong>II. <\/strong>Describe the structures, classifications, functions, and locations of the various types of joints in the human body.<\/p>\r\n\r\n<ol>\r\n \t<li class=\"hanging-indent\">For each of the following types of joints, describe its structure (specific material found between the articulating bones), classification as a fibrous, cartilaginous, or synovial joint (based on the material found between the articulating bones), its function (movements allowed), and one specific location in the human body where it is found (between which two specific named bones):\r\n<ul>\r\n \t<li class=\"hanging-indent\">Suture<\/li>\r\n \t<li class=\"hanging-indent\">Syndesmosis<\/li>\r\n \t<li class=\"hanging-indent\">Gomphosis<\/li>\r\n \t<li class=\"hanging-indent\">Synchondrosis<\/li>\r\n \t<li class=\"hanging-indent\">Symphysis<\/li>\r\n \t<li class=\"hanging-indent\">Synovial joint<\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ol>\r\n<p class=\"hanging-indent\"><strong>III. <\/strong>Describe the structure of a synovial joint and using the knee joint as an example, specify the functions of each component.<\/p>\r\n\r\n<ol>\r\n \t<li class=\"hanging-indent\">Draw a fully-annotated diagram showing the detailed structure of a human knee joint, including each of the following structures:\r\n<ul>\r\n \t<li class=\"hanging-indent\">Articular capsule<\/li>\r\n \t<li class=\"hanging-indent\">Synovial membrane<\/li>\r\n \t<li class=\"hanging-indent\">Synovial cavity<\/li>\r\n \t<li class=\"hanging-indent\">Synovial fluid<\/li>\r\n \t<li class=\"hanging-indent\">Articular cartilage<\/li>\r\n \t<li class=\"hanging-indent\">Ligaments<\/li>\r\n \t<li class=\"hanging-indent\">Tendons<\/li>\r\n \t<li class=\"hanging-indent\">Meniscus<\/li>\r\n \t<li class=\"hanging-indent\">Bursa<\/li>\r\n<\/ul>\r\n<\/li>\r\n \t<li>Describe the function of each of the following structures:\r\n<ul>\r\n \t<li class=\"hanging-indent\">Articular capsule<\/li>\r\n \t<li class=\"hanging-indent\">Synovial membrane<\/li>\r\n \t<li class=\"hanging-indent\">Synovial cavity<\/li>\r\n \t<li class=\"hanging-indent\">Synovial fluid<\/li>\r\n \t<li class=\"hanging-indent\">Articular cartilage<\/li>\r\n \t<li class=\"hanging-indent\">Ligaments<\/li>\r\n \t<li class=\"hanging-indent\">Tendons<\/li>\r\n \t<li class=\"hanging-indent\">Meniscus<\/li>\r\n \t<li class=\"hanging-indent\">Bursa<\/li>\r\n<\/ul>\r\n<\/li>\r\n \t<li class=\"hanging-indent\">Compare and contrast the structure and function of synovial capsules and bursae.<\/li>\r\n<\/ol>\r\n<p class=\"hanging-indent\"><strong>IV.<\/strong> Describe the movements allowed by synovial joints and specify examples of each.<\/p>\r\n\r\n<ol>\r\n \t<li class=\"hanging-indent\">Using complete sentences, describe and provide one example of each of the following movements, including the names of the structure(s) that move in relation to each other:\r\n<ul>\r\n \t<li class=\"hanging-indent\">Gliding movement<\/li>\r\n \t<li class=\"hanging-indent\">Angular movement<\/li>\r\n \t<li class=\"hanging-indent\">Rotation<\/li>\r\n \t<li class=\"hanging-indent\">Circumduction<\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ol>\r\n<p class=\"hanging-indent\"><strong>V.<\/strong> Describe the structures and movements allowed by each type of synovial joint and also specify an example of each in the human body.<\/p>\r\n\r\n<ol>\r\n \t<li class=\"hanging-indent\">For each of the following joint types, describe its structure (material found between the articulating bones), specify its function (movements allowed), and specify one clear example of each by correctly naming the two articulating bones of the joint you are describing:\r\n<ul>\r\n \t<li class=\"hanging-indent\">Pivot joint<\/li>\r\n \t<li class=\"hanging-indent\">Plane joint<\/li>\r\n \t<li class=\"hanging-indent\">Hinge joint<\/li>\r\n \t<li class=\"hanging-indent\">Saddle joint<\/li>\r\n \t<li class=\"hanging-indent\">Condyloid joint<\/li>\r\n \t<li class=\"hanging-indent\">Ball-and-socket joint<\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ol>\r\n<\/div>\r\n<\/div>\r\n&nbsp;\r\n<h2 style=\"text-align: justify\"><strong><a id=\"13-1\"><\/a>Part 1: Overview and Classification of Joints<\/strong><\/h2>\r\n<p style=\"text-align: justify\">The adult human body has 206 bones, and with the exception of the hyoid bone in the neck, each bone is connected to at least one other bone. <strong>Joints,<\/strong> or <strong>articulations,<\/strong> are the location where bones, or bone and cartilage, come together. Many joints allow for movement between the bones. At these joints, the articulating surfaces of the adjacent bones can move smoothly against each other. However, the bones of other joints may be joined to each other by connective tissue or cartilage. These joints are designed for stability and provide for little or no movement. Importantly, joint stability and movement are related to each other. This means that stable joints allow for little or no mobility between the adjacent bones. Conversely, joints that provide the most movement between bones are the least stable. Understanding the relationship between joint structure and function will help to explain why particular types of joints are found in certain areas of the body.<\/p>\r\n<p style=\"text-align: justify\">The articulating surfaces of bones at stable types of joints, with little or no mobility, are strongly united to each other. For example, most of the joints of the skull are held together by fibrous connective tissue and do not allow for movement between the adjacent bones. This lack of mobility is important, because the skull bones serve to protect the brain. Similarly, other joints united by fibrous connective tissue allow for very little movement, which provides stability and weight-bearing support for the body. For example, the tibia and fibula of the leg are tightly united to give stability to the body when standing. At other joints, the bones are held together by cartilage, which permits limited movements between the bones. Thus, the joints of the vertebral column only allow for small movements between adjacent vertebrae, but when added together, these movements provide the flexibility that allows your body to twist, or bend to the front, back, or side. In contrast, at joints that allow for wide ranges of motion, the articulating surfaces of the bones are not directly united to each other. Instead, these surfaces are enclosed within a space filled with lubricating fluid, which allows the bones to move smoothly against each other. These joints provide greater mobility, but since the bones are free to move in relation to each other, the joint is less stable. Most of the joints between the bones of the appendicular skeleton are this freely moveable type of joint. These joints allow the muscles of the body to pull on a bone and thereby produce movement of that body region. Your ability to kick a soccer ball, pick up a fork, and dance the tango depend on mobility at these types of joints.<\/p>\r\n<p style=\"text-align: justify\">Joints are classified both structurally and functionally. Structural classifications of joints take into account whether the adjacent bones are strongly anchored to each other by fibrous connective tissue or cartilage, or whether the adjacent bones articulate with each other within a fluid-filled space called a <strong>[pb_glossary id=\"2883\"]joint cavity[\/pb_glossary]<\/strong>. Functional classifications describe the degree of movement available between the bones, ranging from immobile, to slightly mobile, to freely moveable joints. The amount of movement available at a particular joint of the body is related to the functional requirements for that joint. Thus immobile or slightly moveable joints serve to protect internal organs, give stability to the body, and allow for limited body movement. In contrast, freely moveable joints allow for much more extensive movements of the body and limbs.<\/p>\r\n\r\n<h5 style=\"text-align: justify\"><strong><a id=\"13-1a\"><\/a>Structural Classification of Joints<\/strong><\/h5>\r\n<p style=\"text-align: justify\">The structural classification of joints is based on whether the articulating surfaces of the adjacent bones are directly connected by fibrous connective tissue or cartilage, or whether the articulating surfaces contact each other within a fluid-filled joint cavity. These differences serve to divide the joints of the body into three structural classifications. A <strong>[pb_glossary id=\"2884\"]fibrous joint[\/pb_glossary]<\/strong> is where the adjacent bones are united by fibrous connective tissue. At a <strong>[pb_glossary id=\"2885\"]cartilaginous joint[\/pb_glossary]<\/strong>, the bones are joined by hyaline cartilage or fibrocartilage. At a <strong>[pb_glossary id=\"2886\"]synovial joint[\/pb_glossary]<\/strong>, the articulating surfaces of the bones are not directly connected, but instead come into contact with each other within a joint cavity that is filled with a lubricating fluid. Synovial joints allow for free movement between the bones and are the most common joints of the body.<\/p>\r\n\r\n<h5 style=\"text-align: justify\"><strong><a id=\"13-1b\"><\/a>Functional Classification of Joints<\/strong><\/h5>\r\n<p style=\"text-align: justify\">The functional classification of joints is determined by the amount of mobility found between the adjacent bones. Joints are thus functionally classified as a [pb_glossary id=\"2887\"]synarthrosis[\/pb_glossary] or immobile joint, an [pb_glossary id=\"2888\"]amphiarthrosis[\/pb_glossary] or slightly moveable joint, or as a [pb_glossary id=\"2889\"]diarthrosis[\/pb_glossary], which is a freely moveable joint (arthroun = \u201cto fasten by a joint\u201d). Depending on their location, fibrous joints may be functionally classified as a synarthrosis (immobile joint) or an amphiarthrosis (slightly mobile joint). Cartilaginous joints are also functionally classified as either a synarthrosis or an amphiarthrosis joint. All synovial joints are functionally classified as a diarthrosis joint.<\/p>\r\n<p style=\"text-align: justify\"><strong>Synarthrosis:<\/strong> An immobile or nearly immobile joint is called a synarthrosis. The immobile nature of these joints provides for a strong union between the articulating bones. This is important at locations where the bones provide protection for internal organs. Examples include the sutures, the fibrous joints between the bones of the skull that surround and protect the brain (Figure 1).<\/p>\r\n<p style=\"text-align: justify\"><strong>Amphiarthrosis:<\/strong> An amphiarthrosis is a joint that has limited mobility. An example of this type of joint is the cartilaginous joint that unites the bodies of adjacent vertebrae. Filling the gap between the vertebrae is a thick pad of [pb_glossary id=\"2322\"]fibrocartilage[\/pb_glossary] called an [pb_glossary id=\"2833\"]intervertebral disc[\/pb_glossary] (Figure 2).<\/p>\r\n<p style=\"text-align: justify\">Each intervertebral disc strongly unites the vertebrae but still allows for a limited amount of movement between them. However, the small movements available between adjacent vertebrae can sum together along the length of the vertebral column to provide for large ranges of body movements.<\/p>\r\nAnother example of an amphiarthrosis is the [pb_glossary id=\"2871\"]pubic symphysis[\/pb_glossary] of the pelvis. This is a cartilaginous joint in which the pubic regions of the right and left hip bones are strongly anchored to each other by fibrocartilage. This joint normally has very little mobility. The strength of the pubic symphysis is important in conferring weight-bearing stability to the pelvis.\r\n\r\n[caption id=\"\" align=\"alignnone\" width=\"1220\"]<img src=\"https:\/\/pressbooks.bccampus.ca\/dcbiol110311092nded\/wp-content\/uploads\/sites\/750\/2019\/08\/image1-7.png\" alt=\"image\" width=\"1220\" height=\"1040\" \/> <strong>Figure 1. Suture Joints of Skull.<\/strong> The suture joints of the skull are an example of a synarthrosis, an immobile or essentially immobile joint.[\/caption]\r\n<p style=\"text-align: justify\"><strong>Diarthrosis: <\/strong>A freely mobile joint is classified as a diarthrosis. These types of joints include all synovial joints of the body, which provide the majority of body movements. Most diarthrotic joints are found in the appendicular skeleton and thus give the limbs a wide range of motion.<\/p>\r\n<p style=\"text-align: justify\">This type of [pb_glossary id=\"2890\"]multiaxial[\/pb_glossary] diarthrotic joint allows for movement along three axes (Figure 3). The shoulder and hip joints are multiaxial joints. They allow the upper or lower limb to move in an anterior-posterior direction and a medial-lateral direction. In addition, the limb can also be rotated around its long axis. This third movement results in rotation of the limb so that its anterior surface is moved either toward or away from the midline of the body.<\/p>\r\n\r\n\r\n[caption id=\"\" align=\"alignnone\" width=\"1170\"]<img src=\"https:\/\/pressbooks.bccampus.ca\/dcbiol110311092nded\/wp-content\/uploads\/sites\/750\/2019\/08\/image2-7.png\" alt=\"image\" width=\"1170\" height=\"851\" \/> <strong>Figure 2. Intervertebral Disc.<\/strong> An intervertebral disc unites the bodies of adjacent vertebrae within the vertebral column. Each disc allows for limited movement between the vertebrae and thus functionally forms an amphiarthrosis type of joint. Intervertebral discs are made of fibrocartilage and thereby structurally form a symphysis type of cartilaginous joint.[\/caption]\r\n\r\n[caption id=\"\" align=\"alignnone\" width=\"1665\"]<img src=\"https:\/\/pressbooks.bccampus.ca\/dcbiol110311092nded\/wp-content\/uploads\/sites\/750\/2019\/08\/image3-8.png\" alt=\"image\" width=\"1665\" height=\"966\" \/> <strong>Figure 3. Multiaxial Joint.<\/strong> A multiaxial joint, such as the hip joint, allows for three types of movement: anterior-posterior, medial-lateral, and rotational.[\/caption]\r\n\r\n[caption id=\"\" align=\"alignnone\" width=\"146\"]<img src=\"https:\/\/pressbooks.bccampus.ca\/dcbiol110311092nded\/wp-content\/uploads\/sites\/750\/2019\/08\/image4-7.png\" alt=\"image\" width=\"146\" height=\"143\" \/> Watch <a href=\"https:\/\/youtu.be\/DLxYDoN634c\">this CrashCourse video<\/a> to learn more about joints! Direct link: <a href=\"https:\/\/youtu.be\/DLxYDoN634c\">https:\/\/youtu.be\/DLxYDoN634c<\/a>[\/caption]\r\n<h2 style=\"text-align: justify\"><strong><a id=\"13-2\"><\/a>Part 2: Fibrous Joints<\/strong><\/h2>\r\n<p style=\"text-align: justify\">At a fibrous joint, the adjacent bones are directly connected to each other by fibrous connective tissue, and thus the bones do not have a joint cavity between them (Figure 4). The gap between the bones may be narrow or wide. There are three types of fibrous joints. A [pb_glossary id=\"2822\"]<strong>suture<\/strong>[\/pb_glossary] is the narrow fibrous joint found between most bones of the skull. At a syndesmosis joint, the bones are more widely separated but are held together by a narrow band of fibrous connective tissue called a <strong>[pb_glossary id=\"2735\"]ligament[\/pb_glossary] <\/strong>or a wide sheet of connective tissue called an interosseous membrane. This type of fibrous joint is found between the shaft regions of the long bones in the forearm and in the leg. Lastly, a [pb_glossary id=\"2891\"]gomphosis[\/pb_glossary] is the narrow fibrous joint between the roots of a tooth and the bony socket in the jaw into which the tooth fits.<\/p>\r\n\r\n\r\n[caption id=\"\" align=\"alignnone\" width=\"1674\"]<img src=\"https:\/\/pressbooks.bccampus.ca\/dcbiol110311092nded\/wp-content\/uploads\/sites\/750\/2019\/08\/image5-7.png\" alt=\"image\" width=\"1674\" height=\"734\" \/> <strong>Figure 4. Fibrous Joints.<\/strong> Fibrous joints form strong connections between bones. (a) Sutures join most bones of the skull. (b) An interosseous membrane forms a syndesmosis between the radius and ulna bones of the forearm. (c) A gomphosis is a specialized fibrous joint that anchors a tooth to its socket in the jaw.[\/caption]\r\n<h5 style=\"text-align: justify\"><strong><a id=\"13-2a\"><\/a>Suture<\/strong><\/h5>\r\n<p style=\"text-align: justify\">All the bones of the skull, except for the mandible, are joined to each other by a fibrous joint called a <strong>suture<\/strong>. The fibrous connective tissue found at a suture (\u201cto bind or sew\u201d) strongly unites the adjacent skull bones and thus helps to protect the brain and form the face. In adults, the skull bones are closely opposed, and fibrous connective tissue fills the narrow gap between the bones. The suture is frequently convoluted, forming a tight union that prevents most movement between the bones (Figure 4a). Thus, skull sutures are functionally classified as a [pb_glossary id=\"2887\"]synarthrosis[\/pb_glossary], although some sutures may allow for slight movements between the cranial bones.<\/p>\r\n<p style=\"text-align: justify\">At some sutures, the connective tissue will ossify and be converted into bone, causing the adjacent bones to fuse to each other. Examples of fusions between cranial bones are found both early and late in life. At the time of birth, the [pb_glossary id=\"2825\"]frontal[\/pb_glossary] and [pb_glossary id=\"2832\"]maxillary[\/pb_glossary] bones consist of right and left halves joined together by sutures, which disappear by the eighth year as the halves fuse together to form a single bone. Late in life, the sagittal, coronal, and lambdoid sutures of the skull will begin to ossify and fuse, causing the suture line to gradually disappear.<\/p>\r\n\r\n<h5 style=\"text-align: justify\"><strong><a id=\"13-2b\"><\/a>Syndesmosis<\/strong><\/h5>\r\n<p style=\"text-align: justify\">A <strong>[pb_glossary id=\"2894\"]syndesmosis[\/pb_glossary] <\/strong>(\u201cfastened with a band\u201d) is a type of fibrous joint in which two parallel bones are united to each other by fibrous connective tissue. The gap between the bones may be narrow, with the bones joined by ligaments, or the gap may be wide and filled in by a broad sheet of connective tissue called an <strong>[pb_glossary id=\"2893\"]interosseous membrane[\/pb_glossary]<\/strong>.<\/p>\r\n<p style=\"text-align: justify\">In the forearm, the wide gap between the shaft portions of the radius and ulna bones are strongly united by an interosseous membrane (Figure 4b). Similarly, in the leg, the shafts of the [pb_glossary id=\"2748\"]tibia[\/pb_glossary] and [pb_glossary id=\"2749\"]fibula[\/pb_glossary] are also united by an interosseous membrane. In addition, at the distal tibiofibular joint, the articulating surfaces of the bones lack cartilage and the narrow gap between the bones is anchored by fibrous connective tissue and [pb_glossary id=\"2735\"]ligaments[\/pb_glossary] on both the anterior and posterior aspects of the joint. Together, the interosseous membrane and these ligaments form the tibiofibular syndesmosis.<\/p>\r\n<p style=\"text-align: justify\">The syndesmoses found in the forearm and leg serve to unite parallel bones and prevent their separation. However, a syndesmosis does not prevent all movement between the bones, and thus this type of fibrous joint is functionally classified as an [pb_glossary id=\"2888\"]amphiarthrosis[\/pb_glossary]. In the leg, the syndesmosis between the tibia and fibula strongly unites the bones, allows for little movement, and firmly locks the talus bone in place between the tibia and fibula at the ankle joint. This provides strength and stability to the leg and ankle, which are important during weight bearing. In the forearm, the interosseous membrane is flexible enough to allow for rotation of the radius bone during forearm movements. Thus, in contrast to the stability provided by the tibiofibular syndesmosis, the flexibility of the [pb_glossary id=\"2895\"]antebrachial[\/pb_glossary] interosseous membrane allows for the much greater mobility of the forearm.<\/p>\r\n<p style=\"text-align: justify\"><strong>Gomphosis:<\/strong> A <strong>[pb_glossary id=\"2891\"]gomphosis[\/pb_glossary]<\/strong> (\u201cfastened with bolts\u201d) is the specialized fibrous joint that anchors the root of a tooth into its bony socket within the [pb_glossary id=\"2832\"]maxillary bone[\/pb_glossary] (upper jaw) or [pb_glossary id=\"2820\"]mandible bone[\/pb_glossary] (lower jaw) of the skull. A gomphosis is also known as a peg-and-socket joint. Spanning between the bony walls of the socket and the root of the tooth are numerous short bands of dense connective tissue, each of which is called a <strong>periodontal ligament<\/strong> (see Figure 4c). Due to the immobility of a gomphosis, this type of joint is functionally classified as a [pb_glossary id=\"2887\"]synarthrosis[\/pb_glossary].<\/p>\r\n\r\n<h2 style=\"text-align: justify\"><strong><a id=\"13-3\"><\/a>Part 3: Cartilaginous Joints<\/strong><\/h2>\r\n<p style=\"text-align: justify\">As the name indicates, at a cartilaginous joint, the adjacent bones are united by cartilage, a tough but flexible type of connective tissue.<\/p>\r\n<p style=\"text-align: justify\">These types of joints lack a [pb_glossary id=\"2883\"]joint cavity[\/pb_glossary] and involve bones that are joined together by either [pb_glossary id=\"2321\"]hyaline cartilage[\/pb_glossary] or [pb_glossary id=\"2322\"]fibrocartilage[\/pb_glossary] (Figure 5). There are two types of cartilaginous joints. A synchondrosis is a cartilaginous joint where the bones are joined by hyaline cartilage. Also classified as a synchondrosis are places where bone is united to a cartilage structure, such as between the anterior end of a rib and the costal cartilage of the [pb_glossary id=\"2816\"]thoracic cage[\/pb_glossary]. The second type of cartilaginous joint is a [pb_glossary id=\"2896\"]symphysis[\/pb_glossary], where the bones are joined by fibrocartilage.<\/p>\r\n\r\n\r\n[caption id=\"\" align=\"alignnone\" width=\"1668\"]<img src=\"https:\/\/pressbooks.bccampus.ca\/dcbiol110311092nded\/wp-content\/uploads\/sites\/750\/2019\/08\/image7-7.png\" alt=\"image\" width=\"1668\" height=\"790\" \/> <strong>Figure 5. Cartilaginous Joints.<\/strong> At cartilaginous joints, bones are united by hyaline cartilage to form a synchondrosis or by fibrocartilage to form a symphysis. (a) The hyaline cartilage of the epiphyseal plate (growth plate) forms a synchondrosis that unites the shaft (diaphysis) and end (epiphysis) of a long bone and allows the bone to grow in length. (b) The pubic portions of the right and left hip bones of the pelvis are joined together by fibrocartilage, forming the pubic symphysis.[\/caption]\r\n<h5 style=\"text-align: justify\"><strong><a id=\"13-3a\"><\/a>Synchondrosis<\/strong><\/h5>\r\n<p style=\"text-align: justify\">A <strong>[pb_glossary id=\"2897\"]synchondrosis[\/pb_glossary]<\/strong> (\u201cjoined by cartilage\u201d) is a cartilaginous joint where bones are joined together by hyaline cartilage, or where bone is united to hyaline cartilage. A synchondrosis may be temporary or permanent. A temporary synchondrosis is the [pb_glossary id=\"2760\"]epiphyseal plate[\/pb_glossary] (growth plate) of a growing long bone. The epiphyseal plate is the region of growing hyaline cartilage that unites the [pb_glossary id=\"2756\"]diaphysis[\/pb_glossary] (shaft) of the bone to the [pb_glossary id=\"2757\"]epiphysis[\/pb_glossary] (end of the bone). Bone lengthening involves growth of the epiphyseal plate cartilage and its replacement by bone, which adds to the diaphysis. For many years during childhood growth, the rates of cartilage growth and bone formation are equal and thus the epiphyseal plate does not change in overall thickness as the bone lengthens. During the late teens and early 20s, growth of the cartilage slows and eventually stops. The epiphyseal plate is then completely replaced by bone, and the diaphysis and epiphysis portions of the bone fuse together to form a single adult bone. Once this occurs, bone lengthening ceases. For this reason, the epiphyseal plate is considered to be a temporary synchondrosis. Because cartilage is softer than bone tissue, injury to a growing long bone can damage the epiphyseal plate cartilage, thus stopping bone growth and preventing additional bone lengthening.<\/p>\r\n<p style=\"text-align: justify\">Growing layers of cartilage also form synchondroses that join together the [pb_glossary id=\"2867\"]ilium[\/pb_glossary], [pb_glossary id=\"2868\"]ischium[\/pb_glossary], and [pb_glossary id=\"2869\"]pubic[\/pb_glossary] portions of the hip bone during childhood and adolescence. When body growth stops, the cartilage disappears and is replaced by bone, forming synostoses and fusing the bony components together into the single hip bone of the adult. Similarly, the sacral vertebrae fuse together to form the adult [pb_glossary id=\"2817\"]sacrum[\/pb_glossary].<\/p>\r\n<p style=\"text-align: justify\">Examples of permanent synchondroses are found in the thoracic cage. One example is the first sternocostal joint, where the first rib is anchored to the [pb_glossary id=\"2851\"]manubrium[\/pb_glossary] by its [pb_glossary id=\"2853\"]costal cartilage[\/pb_glossary]. (The articulations of the remaining costal cartilages to the sternum are all synovial joints.) Additional synchondroses are formed where the anterior end of the other 11 ribs is joined to its costal cartilage. Unlike the temporary synchondroses of the epiphyseal plate, these permanent synchondroses retain their hyaline cartilage and thus do not ossify with age. Due to the lack of movement between the bone and cartilage, both temporary and permanent synchondroses are functionally classified as a synarthrosis.<\/p>\r\n<p style=\"text-align: justify\"><strong>Symphysis:<\/strong> A cartilaginous joint where the bones are joined by fibrocartilage is called a <strong>[pb_glossary id=\"2896\"]symphysis[\/pb_glossary] <\/strong>(\u201cgrowing together\u201d). Fibrocartilage is very strong because it contains numerous bundles of thick collagen fibers, thus giving it a much greater ability to resist pulling and bending forces when compared with hyaline cartilage. This gives symphyses the ability to strongly unite the adjacent bones but can still allow for limited movement to occur. Thus, a symphysis is functionally classified as an [pb_glossary id=\"2888\"]amphiarthrosis[\/pb_glossary].<\/p>\r\n<p style=\"text-align: justify\">The gap separating the bones at a symphysis may be narrow or wide. An example in which the gap between the bones is narrow is the [pb_glossary id=\"2871\"]pubic symphysis[\/pb_glossary], where the pubic portions of the right and left hip bones of the pelvis are joined together by fibrocartilage across a narrow gap.<\/p>\r\n<p style=\"text-align: justify\">The intervertebral symphysis is a wide symphysis located between the bodies of adjacent vertebrae of the vertebral column. Here a thick pad of [pb_glossary id=\"2322\"]fibrocartilage[\/pb_glossary] called an intervertebral disc strongly unites the adjacent vertebrae by filling the gap between them. The width of the intervertebral symphysis is important because it allows for small movements between the adjacent vertebrae. In addition, the thick [pb_glossary id=\"2833\"]intervertebral disc[\/pb_glossary] provides cushioning between the vertebrae, which is important when carrying heavy objects or during high-impact activities such as running or jumping.<\/p>\r\n\r\n<h2 style=\"text-align: justify\"><strong><a id=\"13-4\"><\/a>Part 4: Synovial Joints<\/strong><\/h2>\r\n<p style=\"text-align: justify\">[pb_glossary id=\"2886\"]Synovial joints[\/pb_glossary] are the most common type of joint in the body (Figure 6). A key structural characteristic for a synovial joint that is not seen at fibrous or cartilaginous joints is the presence of a joint cavity. This fluid-filled space is the site at which the articulating surfaces of the bones contact each other. Also, unlike fibrous or cartilaginous joints, the articulating bone surfaces at a synovial joint are not directly connected to each other with fibrous connective tissue or cartilage. This gives the bones of a synovial joint the ability to move smoothly against each other, allowing for increased joint mobility.<\/p>\r\n\r\n<h5 style=\"text-align: justify\"><strong><a id=\"13-4a\"><\/a>Structural Features of Synovial Joints<\/strong><\/h5>\r\n<p style=\"text-align: justify\">Synovial joints are characterized by the presence of a joint cavity. The walls of this space are formed by the <strong>[pb_glossary id=\"2898\"]articular capsule[\/pb_glossary]<\/strong>, a fibrous connective tissue structure that is attached to each bone just outside the area of the bone\u2019s articulating surface. The bones of the joint articulate with each other within the joint cavity.<\/p>\r\n<p style=\"text-align: justify\">Friction between the bones at a synovial joint is prevented by the presence of the <strong>[pb_glossary id=\"2763\"]articular cartilage[\/pb_glossary]<\/strong>, a thin layer of [pb_glossary id=\"2321\"]hyaline cartilage[\/pb_glossary] that covers the entire articulating surface of each bone. However, unlike at a cartilaginous joint, the articular cartilages of each bone are not continuous with each other. Instead, the articular cartilage acts like a Teflon\u00ae coating over the bone surface, allowing the articulating bones to move smoothly against each other without damaging the underlying bone tissue. Lining the inner surface of the articular capsule is a thin <strong>[pb_glossary id=\"2899\"]synovial membrane[\/pb_glossary]<\/strong>. The cells of this membrane secrete <strong>[pb_glossary id=\"2107\"]synovial fluid[\/pb_glossary]<\/strong> (synovia = \u201ca thick fluid\u201d), a thick, slimy fluid that provides lubrication to further reduce friction between the bones of the joint. This fluid also provides nourishment to the articular cartilage, which does not contain blood vessels. The ability of the bones to move smoothly against each other within the joint cavity, and the freedom of joint movement this provides, means that each synovial joint is functionally classified as a [pb_glossary id=\"2889\"]diarthrosis[\/pb_glossary].<\/p>\r\n\r\n\r\n[caption id=\"\" align=\"alignnone\" width=\"946\"]<img src=\"https:\/\/pressbooks.bccampus.ca\/dcbiol110311092nded\/wp-content\/uploads\/sites\/750\/2019\/08\/image8-8.png\" alt=\"image\" width=\"946\" height=\"1027\" \/> <strong>Figure 6. Synovial Joints.<\/strong> Synovial joints allow for smooth movements between the adjacent bones. The joint is surrounded by an articular capsule that defines a joint cavity filled with synovial fluid. The articulating surfaces of the bones are covered by a thin layer of articular cartilage. Ligaments support the joint by holding the bones together and resisting excess or abnormal joint motions.[\/caption]\r\n<p style=\"text-align: justify\">Outside of their articulating surfaces, the bones are connected together by <strong>[pb_glossary id=\"2735\"]ligaments[\/pb_glossary],<\/strong> which are strong bands of fibrous connective tissue. These strengthen and support the joint by anchoring the bones together and preventing their separation. Ligaments allow for normal movements at a joint, but limit the range of these motions, thus preventing excessive or abnormal joint movements.<\/p>\r\n<p style=\"text-align: justify\">At many synovial joints, additional support is provided by the muscles and their tendons that act across the joint. A <strong>[pb_glossary id=\"2736\"]tendon[\/pb_glossary]<\/strong> is the dense connective tissue structure that attaches a muscle to bone. As forces acting on a joint increase, the body will automatically increase the overall strength of contraction of the muscles crossing that joint, thus allowing the muscle and its tendon to serve as a \u201cdynamic ligament\u201d to resist forces and support the joint. This type of indirect support by muscles is very important at the shoulder joint, for example, where the ligaments are relatively weak.<\/p>\r\n\r\n<h5 style=\"text-align: justify\"><strong><a id=\"13-4b\"><\/a>Additional Structures Associated with Synovial Joints<\/strong><\/h5>\r\n<p style=\"text-align: justify\">A few synovial joints of the body have a fibrocartilage structure located between the articulating bones. This is called an <strong>[pb_glossary id=\"2900\"]articular disc[\/pb_glossary]<\/strong>, which is generally small and oval-shaped, or a <strong>[pb_glossary id=\"2901\"]meniscus[\/pb_glossary]<\/strong>, which is larger and C-shaped. These structures can serve several functions, depending on the specific joint. In some places, an articular disc may act to strongly unite the bones of the joint to each other. Examples of this include the articular discs found at the sternoclavicular joint or between the distal ends of the [pb_glossary id=\"2747\"]radius[\/pb_glossary] and [pb_glossary id=\"2745\"]ulna[\/pb_glossary] bones. At other synovial joints, the disc can provide shock absorption and cushioning between the bones, which is the function of each meniscus within the knee joint. Finally, an articular disc can serve to smooth the movements between the articulating bones, as seen at the temporomandibular joint. Some synovial joints also have a fat pad, which can serve as a cushion between the bones.<\/p>\r\n<p style=\"text-align: justify\">Additional structures located outside of a synovial joint serve to prevent friction between the bones of the joint and the overlying muscle tendons or skin. A <strong>[pb_glossary id=\"2902\"]bursa[\/pb_glossary]<\/strong> (plural = bursae) is a thin connective tissue sac filled with lubricating liquid. They are located in regions where skin, ligaments, muscles, or muscle tendons can rub against each other, usually near a body joint (Figure 7). Bursae reduce friction by separating the adjacent structures, preventing them from rubbing directly against each other.<\/p>\r\n\r\n\r\n[caption id=\"\" align=\"alignnone\" width=\"1303\"]<img src=\"https:\/\/pressbooks.bccampus.ca\/dcbiol110311092nded\/wp-content\/uploads\/sites\/750\/2019\/08\/image9-7.png\" alt=\"image\" width=\"1303\" height=\"1029\" \/> <strong>Figure 7. Bursae.<\/strong> Bursae are fluid-filled sacs that serve to prevent friction between skin, muscle, or tendon and an underlying bone. Three major bursae and a fat pad are part of the complex joint that unites the femur and tibia of the leg.[\/caption]\r\n<h5 style=\"text-align: justify\"><strong><a id=\"13-4c\"><\/a>Types of Synovial Joints<\/strong><\/h5>\r\n<p style=\"text-align: justify\">Synovial joints are subdivided based on the shapes of the articulating surfaces of the bones that form each joint. The six types of synovial joints are pivot, hinge, condyloid, saddle, plane (gliding), and ball-and socket-joints (Figure 8).<\/p>\r\n<p style=\"text-align: justify\"><strong>1. Pivot Joint:<\/strong> At a <strong>[pb_glossary id=\"2903\"]pivot joint[\/pb_glossary]<\/strong>, a rounded portion of a bone is enclosed within a ring formed partially by the articulation with another bone and partially by a ligament (Figure 8a). The bone rotates within this ring. Since the rotation is around a single axis, pivot joints are functionally classified as a [pb_glossary id=\"2904\"]uniaxial joint[\/pb_glossary]. An example of a pivot joint is the atlantoaxial joint, found between the C1 ([pb_glossary id=\"2848\"]atlas[\/pb_glossary]) and C2 ([pb_glossary id=\"2849\"]axis[\/pb_glossary]) vertebrae. Here, the upward projecting dens of the axis articulates with the inner aspect of the atlas, where it is held in place by a ligament. Rotation at this joint allows you to turn your head from side to side. A second pivot joint is found at the <strong>proximal radioulnar joint<\/strong>. Here, the head of the [pb_glossary id=\"2747\"]radius[\/pb_glossary] is largely encircled by a ligament that holds it in place as it articulates with the radial notch of the [pb_glossary id=\"2745\"]ulna[\/pb_glossary]. Rotation of the radius allows for forearm movements.<\/p>\r\n<p style=\"text-align: justify\"><strong>2. Hinge Joint:<\/strong> In a <strong>hinge joint<\/strong>, the convex end of one bone articulates with the [pb_glossary id=\"2912\"]concave[\/pb_glossary] end of the adjoining bone (Figure 8b). This type of joint allows only for angular movements - bending and straightening motions along a single axis - and thus hinge joints are functionally classified as [pb_glossary id=\"2904\"]uniaxial joints[\/pb_glossary]. A good example is the elbow joint, with the articulation between the [pb_glossary id=\"2746\"]humerus[\/pb_glossary] and the [pb_glossary id=\"2745\"]ulna[\/pb_glossary]. Other hinge joints of the body include the knee, ankle, and interphalangeal joints between the [pb_glossary id=\"2750\"]phalanx[\/pb_glossary] bones of the fingers and toes.<\/p>\r\n<p style=\"text-align: justify\"><strong>3. Condyloid Joint:<\/strong> At a <strong>[pb_glossary id=\"2910\"]condyloid joint[\/pb_glossary]<\/strong> (ellipsoid joint), the shallow depression at the end of one bone articulates with a rounded structure from an adjacent bone or bones (Figure 8e). The knuckle (metacarpophalangeal) joints of the hand between the distal end of a [pb_glossary id=\"2744\"]metacarpal[\/pb_glossary] bone and the [pb_glossary id=\"2373\"]proximal[\/pb_glossary] [pb_glossary id=\"2750\"]phalanx[\/pb_glossary] bone are condyloid joints. Another example is the radiocarpal joint of the wrist, between the shallow depression at the [pb_glossary id=\"2374\"]distal[\/pb_glossary] end of the radius bone and three of the [pb_glossary id=\"2752\"]carpal[\/pb_glossary] bones. In this case, the articulation area has a more oval (elliptical) shape. Functionally, condyloid joints are [pb_glossary id=\"2909\"]biaxial joints[\/pb_glossary] that allow for two planes of angular movement. One movement involves the bending and straightening of the fingers or the anterior-posterior movements of the hand. The second movement is a side-to-side movement, which allows you to spread your fingers apart and bring them together, or to move your hand in a medial-going or lateral-going direction.<\/p>\r\n<p style=\"text-align: justify\"><strong>4. Saddle Joint:<\/strong> At a [pb_glossary id=\"2907\"]<strong>saddle joint<\/strong>[\/pb_glossary], both of the articulating surfaces for the bones have a saddle shape, which is concave in one direction and [pb_glossary id=\"2908\"]convex[\/pb_glossary] in the other (Figure 8c). This allows the two bones to fit together like a rider sitting on a saddle. Saddle joints are functionally classified as [pb_glossary id=\"2909\"]biaxial joints[\/pb_glossary]. The primary example is the first carpometacarpal joint, between the trapezium (a [pb_glossary id=\"2752\"]carpal[\/pb_glossary] bone) and the first [pb_glossary id=\"2744\"]metacarpal[\/pb_glossary] bone at the base of the thumb. This joint provides the thumb the ability for angular movement away from the palm of the hand along two planes. Thus, the thumb can move within the same plane as the palm of the hand, or it can jut out anteriorly, perpendicular to the palm. This movement of the first carpometacarpal joint is what gives humans their distinctive \u201copposable\u201d thumbs. The sternoclavicular joint is also classified as a saddle joint.<\/p>\r\n<p style=\"text-align: justify\"><strong>5. Plane Joint:<\/strong> At a <strong>[pb_glossary id=\"2905\"]plane joint[\/pb_glossary]<\/strong> (gliding joint), the articulating surfaces of the bones are flat or slightly curved and of approximately the same size, which allows for predominantly gliding movement where the bones slide back and forth against each other (Figure 8d). The motion at this type of joint is usually small and tightly constrained by surrounding ligaments. It is worth noting that based only on their shape, plane joints have the ability to allow multiple movements, including rotation. Thus, plane joints can be functionally classified as a [pb_glossary id=\"2913\"]multiaxial joint[\/pb_glossary]. However, not all of these movements are available to every plane joint due to limitations placed on it by ligaments or neighboring bones. Thus, depending upon the specific joint of the body, a plane joint may exhibit only a single type of movement or several movements. Plane joints are found between the [pb_glossary id=\"2752\"]carpal[\/pb_glossary] bones (intercarpal joints) of the wrist or [pb_glossary id=\"2753\"]tarsal[\/pb_glossary] bones (intertarsal joints) of the foot, between the [pb_glossary id=\"2786\"]clavicle[\/pb_glossary] and acromion of the [pb_glossary id=\"2755\"]scapula[\/pb_glossary] (acromioclavicular joint), and between the [pb_glossary id=\"2359\"]superior[\/pb_glossary] and [pb_glossary id=\"2360\"]inferior[\/pb_glossary] articular processes of adjacent vertebrae (zygapophysial joints).<\/p>\r\n<p style=\"text-align: justify\"><strong>6. Ball-and-Socket Joint:<\/strong> The joint with the greatest range of motion is the <strong>[pb_glossary id=\"2906\"]ball-and-socket joint[\/pb_glossary]<\/strong>. At these joints, the rounded head of one bone (the ball) fits into the [pb_glossary id=\"2912\"]concave[\/pb_glossary] articulation (the socket) of the adjacent bone (Figure 8f). The hip joint and the glenohumeral (shoulder) joint are the only ball-and-socket joints of the body. At the hip joint, the head of the femur articulates with the [pb_glossary id=\"2914\"]acetabulum[\/pb_glossary] of the hip bone, and at the shoulder joint, the head of the humerus articulates with the glenoid cavity of the [pb_glossary id=\"2755\"]scapula[\/pb_glossary].<\/p>\r\n<p style=\"text-align: justify\">Ball-and-socket joints are classified functionally as [pb_glossary id=\"2913\"]multiaxial joints[\/pb_glossary]. The [pb_glossary id=\"2379\"]femur[\/pb_glossary] and the [pb_glossary id=\"2746\"]humerus[\/pb_glossary] are able to effect angular movements in both anterior-posterior and medial-lateral directions and they can also rotate around their long axis. These multiaxial joints also allow for a complex movement called [pb_glossary id=\"2915\"]circumduction[\/pb_glossary]. In this instance, the distal end of the bone moves in a circle while the proximal end remains relatively stationary. Circumduction of the arm and leg are possible at ball-and-socket joints.<\/p>\r\n<p style=\"text-align: justify\">The shallow socket formed by the [pb_glossary id=\"2863\"]glenoid cavity[\/pb_glossary] allows the shoulder joint an extensive range of motion. In contrast, the deep socket of the [pb_glossary id=\"2914\"]acetabulum[\/pb_glossary] and the strong supporting ligaments of the hip joint serve to constrain movements of the femur, reflecting the need for stability and weight-bearing ability at the hip.<\/p>\r\n\r\n\r\n[caption id=\"\" align=\"alignnone\" width=\"878\"]<img src=\"https:\/\/pressbooks.bccampus.ca\/dcbiol110311092nded\/wp-content\/uploads\/sites\/750\/2019\/08\/image10-7.png\" alt=\"image\" width=\"878\" height=\"1038\" \/> <strong>Figure 8. Types of Synovial Joints.<\/strong> The six types of synovial joints allow the body to move in a variety of ways. (a) Pivot joints allow for rotation around an axis, such as between the first and second cervical vertebrae, which allows for side-to-side rotation of the head. (b) The hinge joint of the elbow works like a door hinge. (c) The articulation between the trapezium carpal bone and the first metacarpal bone at the base of the thumb is a saddle joint. (d) Plane joints, such as those between the tarsal bones of the foot, allow for limited gliding movements between bones. (e) The radiocarpal joint of the wrist is a condyloid joint. (f) The hip and shoulder joints are the only ball-and-socket joints of the body.[\/caption]\r\n\r\n<div class=\"textbox textbox--exercises\"><header class=\"textbox__header\">\r\n<p class=\"textbox__title\"><a id=\"P\"><\/a>Practice Questions<\/p>\r\n\r\n<\/header>\r\n<div class=\"textbox__content\">\r\n\r\n<strong>Part 1:<\/strong> Overview and Classification of Joints\r\n\r\n[h5p id=\"49\"]\r\n\r\n[h5p id=\"45\"]\r\n\r\n<strong>Part 2: <\/strong>Fibrous Joints\r\n\r\n[h5p id=\"47\"]\r\n\r\n[h5p id=\"48\"]\r\n\r\n<strong>Part 3:<\/strong> Cartilaginous Joints\r\n\r\n[h5p id=\"51\"]\r\n\r\n[h5p id=\"52\"]\r\n\r\n[h5p id=\"53\"]\r\n\r\n<strong>Part 4:<\/strong> Synovial Joints\r\n\r\n[h5p id=\"46\"]\r\n\r\n[h5p id=\"50\"]\r\n\r\n[h5p id=\"54\"]\r\n\r\n[h5p id=\"55\"]\r\n\r\n[h5p id=\"56\"]\r\n\r\n[h5p id=\"57\"]\r\n\r\n[h5p id=\"58\"]\r\n\r\n[h5p id=\"59\"]\r\n\r\n[h5p id=\"60\"]\r\n\r\n[h5p id=\"61\"]\r\n\r\n<\/div>\r\n<\/div>\r\n&nbsp;\r\n\r\n<\/div>","rendered":"<div class=\"unit-13:-joints\">\n<div class=\"textbox shaded\">\n<p><strong>Unit outline<\/strong><\/p>\n<p><strong>Joints<\/strong><\/p>\n<p><a href=\"#13-1\"><strong>Part 1:<\/strong> Overview and Classification of Joints<\/a><\/p>\n<ul>\n<li><a href=\"#13-1a\">Structural classification<\/a><\/li>\n<li><a href=\"#13-1b\">Functional classification<\/a><\/li>\n<\/ul>\n<p><a href=\"#13-2\"><strong>Part 2: <\/strong>Fibrous Joints<\/a><\/p>\n<ul>\n<li><a href=\"#13-2a\">Suture<\/a><\/li>\n<li><a href=\"#13-2b\">Syndesmosis<\/a><\/li>\n<li><a href=\"#13-2c\">Gomphosis<\/a><\/li>\n<\/ul>\n<p><a href=\"#13-3\"><strong>Part 3:<\/strong> Cartilaginous Joints<\/a><\/p>\n<ul>\n<li><a href=\"#13-3a\">Synchondrosis<\/a><\/li>\n<li><a href=\"#13-3b\">Symphysis<\/a><\/li>\n<\/ul>\n<p><a href=\"#13-4\"><strong>Part 4:<\/strong> Synovial Joints<\/a><\/p>\n<ul>\n<li><a href=\"#13-4a\">Structural features of synovial joints<\/a><\/li>\n<li><a href=\"#13-4b\">Additional structures associated with synovial joints<\/a><\/li>\n<li><a href=\"#13-4c\">Types of synovial joints<\/a><\/li>\n<\/ul>\n<h2><a href=\"#P\">Practice Questions<\/a><\/h2>\n<\/div>\n<div class=\"textbox textbox--learning-objectives\">\n<header class=\"textbox__header\">\n<p class=\"textbox__title\"><strong>Learning Objectives<\/strong><\/p>\n<\/header>\n<div class=\"textbox__content\">\n<p>At the end of this unit, you should be able to:<\/p>\n<p class=\"hanging-indent\"><strong>I.<\/strong> Explain what is meant by the terms synarthrotic, diarthrotic, and amphiarthrotic as descriptions of the functional classes of joints.<\/p>\n<p class=\"hanging-indent\"><strong>II. <\/strong>Describe the structures, classifications, functions, and locations of the various types of joints in the human body.<\/p>\n<p class=\"hanging-indent\"><strong>III. <\/strong>Describe the structure of a synovial joint and using the knee joint as an example, specify the functions of each component.<\/p>\n<p class=\"hanging-indent\"><strong>IV.<\/strong> Describe the movements allowed by synovial joints and specify examples of each.<\/p>\n<p class=\"hanging-indent\"><strong>V.<\/strong> Describe the structures and movements allowed by each type of synovial joint and also specify an example of each in the human body.<\/p>\n<\/div>\n<\/div>\n<div class=\"textbox textbox--learning-objectives\">\n<header class=\"textbox__header\">\n<p class=\"textbox__title\"><strong>Learning Objectives and Guiding Questions<\/strong><\/p>\n<\/header>\n<div class=\"textbox__content\">\n<p>At the end of this unit, you should be able to complete all the following tasks, including answering the guiding questions associated with each task.<\/p>\n<p class=\"hanging-indent\"><strong>I.<\/strong> Explain what is meant by the terms synarthrotic, diarthrotic, and amphiarthrotic as descriptions of the functional classes of joints.<\/p>\n<ol>\n<li class=\"hanging-indent\">Define each of the following terms:\n<ul>\n<li class=\"hanging-indent\">Synarthrotic joint<\/li>\n<li class=\"hanging-indent\">Diarthrotic joint<\/li>\n<li class=\"hanging-indent\">Amphiarthrotic joint<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n<p class=\"hanging-indent\"><strong>II. <\/strong>Describe the structures, classifications, functions, and locations of the various types of joints in the human body.<\/p>\n<ol>\n<li class=\"hanging-indent\">For each of the following types of joints, describe its structure (specific material found between the articulating bones), classification as a fibrous, cartilaginous, or synovial joint (based on the material found between the articulating bones), its function (movements allowed), and one specific location in the human body where it is found (between which two specific named bones):\n<ul>\n<li class=\"hanging-indent\">Suture<\/li>\n<li class=\"hanging-indent\">Syndesmosis<\/li>\n<li class=\"hanging-indent\">Gomphosis<\/li>\n<li class=\"hanging-indent\">Synchondrosis<\/li>\n<li class=\"hanging-indent\">Symphysis<\/li>\n<li class=\"hanging-indent\">Synovial joint<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n<p class=\"hanging-indent\"><strong>III. <\/strong>Describe the structure of a synovial joint and using the knee joint as an example, specify the functions of each component.<\/p>\n<ol>\n<li class=\"hanging-indent\">Draw a fully-annotated diagram showing the detailed structure of a human knee joint, including each of the following structures:\n<ul>\n<li class=\"hanging-indent\">Articular capsule<\/li>\n<li class=\"hanging-indent\">Synovial membrane<\/li>\n<li class=\"hanging-indent\">Synovial cavity<\/li>\n<li class=\"hanging-indent\">Synovial fluid<\/li>\n<li class=\"hanging-indent\">Articular cartilage<\/li>\n<li class=\"hanging-indent\">Ligaments<\/li>\n<li class=\"hanging-indent\">Tendons<\/li>\n<li class=\"hanging-indent\">Meniscus<\/li>\n<li class=\"hanging-indent\">Bursa<\/li>\n<\/ul>\n<\/li>\n<li>Describe the function of each of the following structures:\n<ul>\n<li class=\"hanging-indent\">Articular capsule<\/li>\n<li class=\"hanging-indent\">Synovial membrane<\/li>\n<li class=\"hanging-indent\">Synovial cavity<\/li>\n<li class=\"hanging-indent\">Synovial fluid<\/li>\n<li class=\"hanging-indent\">Articular cartilage<\/li>\n<li class=\"hanging-indent\">Ligaments<\/li>\n<li class=\"hanging-indent\">Tendons<\/li>\n<li class=\"hanging-indent\">Meniscus<\/li>\n<li class=\"hanging-indent\">Bursa<\/li>\n<\/ul>\n<\/li>\n<li class=\"hanging-indent\">Compare and contrast the structure and function of synovial capsules and bursae.<\/li>\n<\/ol>\n<p class=\"hanging-indent\"><strong>IV.<\/strong> Describe the movements allowed by synovial joints and specify examples of each.<\/p>\n<ol>\n<li class=\"hanging-indent\">Using complete sentences, describe and provide one example of each of the following movements, including the names of the structure(s) that move in relation to each other:\n<ul>\n<li class=\"hanging-indent\">Gliding movement<\/li>\n<li class=\"hanging-indent\">Angular movement<\/li>\n<li class=\"hanging-indent\">Rotation<\/li>\n<li class=\"hanging-indent\">Circumduction<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n<p class=\"hanging-indent\"><strong>V.<\/strong> Describe the structures and movements allowed by each type of synovial joint and also specify an example of each in the human body.<\/p>\n<ol>\n<li class=\"hanging-indent\">For each of the following joint types, describe its structure (material found between the articulating bones), specify its function (movements allowed), and specify one clear example of each by correctly naming the two articulating bones of the joint you are describing:\n<ul>\n<li class=\"hanging-indent\">Pivot joint<\/li>\n<li class=\"hanging-indent\">Plane joint<\/li>\n<li class=\"hanging-indent\">Hinge joint<\/li>\n<li class=\"hanging-indent\">Saddle joint<\/li>\n<li class=\"hanging-indent\">Condyloid joint<\/li>\n<li class=\"hanging-indent\">Ball-and-socket joint<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n<\/div>\n<\/div>\n<p>&nbsp;<\/p>\n<h2 style=\"text-align: justify\"><strong><a id=\"13-1\"><\/a>Part 1: Overview and Classification of Joints<\/strong><\/h2>\n<p style=\"text-align: justify\">The adult human body has 206 bones, and with the exception of the hyoid bone in the neck, each bone is connected to at least one other bone. <strong>Joints,<\/strong> or <strong>articulations,<\/strong> are the location where bones, or bone and cartilage, come together. Many joints allow for movement between the bones. At these joints, the articulating surfaces of the adjacent bones can move smoothly against each other. However, the bones of other joints may be joined to each other by connective tissue or cartilage. These joints are designed for stability and provide for little or no movement. Importantly, joint stability and movement are related to each other. This means that stable joints allow for little or no mobility between the adjacent bones. Conversely, joints that provide the most movement between bones are the least stable. Understanding the relationship between joint structure and function will help to explain why particular types of joints are found in certain areas of the body.<\/p>\n<p style=\"text-align: justify\">The articulating surfaces of bones at stable types of joints, with little or no mobility, are strongly united to each other. For example, most of the joints of the skull are held together by fibrous connective tissue and do not allow for movement between the adjacent bones. This lack of mobility is important, because the skull bones serve to protect the brain. Similarly, other joints united by fibrous connective tissue allow for very little movement, which provides stability and weight-bearing support for the body. For example, the tibia and fibula of the leg are tightly united to give stability to the body when standing. At other joints, the bones are held together by cartilage, which permits limited movements between the bones. Thus, the joints of the vertebral column only allow for small movements between adjacent vertebrae, but when added together, these movements provide the flexibility that allows your body to twist, or bend to the front, back, or side. In contrast, at joints that allow for wide ranges of motion, the articulating surfaces of the bones are not directly united to each other. Instead, these surfaces are enclosed within a space filled with lubricating fluid, which allows the bones to move smoothly against each other. These joints provide greater mobility, but since the bones are free to move in relation to each other, the joint is less stable. Most of the joints between the bones of the appendicular skeleton are this freely moveable type of joint. These joints allow the muscles of the body to pull on a bone and thereby produce movement of that body region. Your ability to kick a soccer ball, pick up a fork, and dance the tango depend on mobility at these types of joints.<\/p>\n<p style=\"text-align: justify\">Joints are classified both structurally and functionally. Structural classifications of joints take into account whether the adjacent bones are strongly anchored to each other by fibrous connective tissue or cartilage, or whether the adjacent bones articulate with each other within a fluid-filled space called a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2883\">joint cavity<\/a><\/strong>. Functional classifications describe the degree of movement available between the bones, ranging from immobile, to slightly mobile, to freely moveable joints. The amount of movement available at a particular joint of the body is related to the functional requirements for that joint. Thus immobile or slightly moveable joints serve to protect internal organs, give stability to the body, and allow for limited body movement. In contrast, freely moveable joints allow for much more extensive movements of the body and limbs.<\/p>\n<h5 style=\"text-align: justify\"><strong><a id=\"13-1a\"><\/a>Structural Classification of Joints<\/strong><\/h5>\n<p style=\"text-align: justify\">The structural classification of joints is based on whether the articulating surfaces of the adjacent bones are directly connected by fibrous connective tissue or cartilage, or whether the articulating surfaces contact each other within a fluid-filled joint cavity. These differences serve to divide the joints of the body into three structural classifications. A <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2884\">fibrous joint<\/a><\/strong> is where the adjacent bones are united by fibrous connective tissue. At a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2885\">cartilaginous joint<\/a><\/strong>, the bones are joined by hyaline cartilage or fibrocartilage. At a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2886\">synovial joint<\/a><\/strong>, the articulating surfaces of the bones are not directly connected, but instead come into contact with each other within a joint cavity that is filled with a lubricating fluid. Synovial joints allow for free movement between the bones and are the most common joints of the body.<\/p>\n<h5 style=\"text-align: justify\"><strong><a id=\"13-1b\"><\/a>Functional Classification of Joints<\/strong><\/h5>\n<p style=\"text-align: justify\">The functional classification of joints is determined by the amount of mobility found between the adjacent bones. Joints are thus functionally classified as a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2887\">synarthrosis<\/a> or immobile joint, an <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2888\">amphiarthrosis<\/a> or slightly moveable joint, or as a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2889\">diarthrosis<\/a>, which is a freely moveable joint (arthroun = \u201cto fasten by a joint\u201d). Depending on their location, fibrous joints may be functionally classified as a synarthrosis (immobile joint) or an amphiarthrosis (slightly mobile joint). Cartilaginous joints are also functionally classified as either a synarthrosis or an amphiarthrosis joint. All synovial joints are functionally classified as a diarthrosis joint.<\/p>\n<p style=\"text-align: justify\"><strong>Synarthrosis:<\/strong> An immobile or nearly immobile joint is called a synarthrosis. The immobile nature of these joints provides for a strong union between the articulating bones. This is important at locations where the bones provide protection for internal organs. Examples include the sutures, the fibrous joints between the bones of the skull that surround and protect the brain (Figure 1).<\/p>\n<p style=\"text-align: justify\"><strong>Amphiarthrosis:<\/strong> An amphiarthrosis is a joint that has limited mobility. An example of this type of joint is the cartilaginous joint that unites the bodies of adjacent vertebrae. Filling the gap between the vertebrae is a thick pad of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2322\">fibrocartilage<\/a> called an <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2833\">intervertebral disc<\/a> (Figure 2).<\/p>\n<p style=\"text-align: justify\">Each intervertebral disc strongly unites the vertebrae but still allows for a limited amount of movement between them. However, the small movements available between adjacent vertebrae can sum together along the length of the vertebral column to provide for large ranges of body movements.<\/p>\n<p>Another example of an amphiarthrosis is the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2871\">pubic symphysis<\/a> of the pelvis. This is a cartilaginous joint in which the pubic regions of the right and left hip bones are strongly anchored to each other by fibrocartilage. This joint normally has very little mobility. The strength of the pubic symphysis is important in conferring weight-bearing stability to the pelvis.<\/p>\n<figure style=\"width: 1220px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/dcbiol110311092nded\/wp-content\/uploads\/sites\/750\/2019\/08\/image1-7.png\" alt=\"image\" width=\"1220\" height=\"1040\" \/><figcaption class=\"wp-caption-text\"><strong>Figure 1. Suture Joints of Skull.<\/strong> The suture joints of the skull are an example of a synarthrosis, an immobile or essentially immobile joint.<\/figcaption><\/figure>\n<p style=\"text-align: justify\"><strong>Diarthrosis: <\/strong>A freely mobile joint is classified as a diarthrosis. These types of joints include all synovial joints of the body, which provide the majority of body movements. Most diarthrotic joints are found in the appendicular skeleton and thus give the limbs a wide range of motion.<\/p>\n<p style=\"text-align: justify\">This type of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2890\">multiaxial<\/a> diarthrotic joint allows for movement along three axes (Figure 3). The shoulder and hip joints are multiaxial joints. They allow the upper or lower limb to move in an anterior-posterior direction and a medial-lateral direction. In addition, the limb can also be rotated around its long axis. This third movement results in rotation of the limb so that its anterior surface is moved either toward or away from the midline of the body.<\/p>\n<figure style=\"width: 1170px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/dcbiol110311092nded\/wp-content\/uploads\/sites\/750\/2019\/08\/image2-7.png\" alt=\"image\" width=\"1170\" height=\"851\" \/><figcaption class=\"wp-caption-text\"><strong>Figure 2. Intervertebral Disc.<\/strong> An intervertebral disc unites the bodies of adjacent vertebrae within the vertebral column. Each disc allows for limited movement between the vertebrae and thus functionally forms an amphiarthrosis type of joint. Intervertebral discs are made of fibrocartilage and thereby structurally form a symphysis type of cartilaginous joint.<\/figcaption><\/figure>\n<figure style=\"width: 1665px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/dcbiol110311092nded\/wp-content\/uploads\/sites\/750\/2019\/08\/image3-8.png\" alt=\"image\" width=\"1665\" height=\"966\" \/><figcaption class=\"wp-caption-text\"><strong>Figure 3. Multiaxial Joint.<\/strong> A multiaxial joint, such as the hip joint, allows for three types of movement: anterior-posterior, medial-lateral, and rotational.<\/figcaption><\/figure>\n<figure style=\"width: 146px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/dcbiol110311092nded\/wp-content\/uploads\/sites\/750\/2019\/08\/image4-7.png\" alt=\"image\" width=\"146\" height=\"143\" \/><figcaption class=\"wp-caption-text\">Watch <a href=\"https:\/\/youtu.be\/DLxYDoN634c\">this CrashCourse video<\/a> to learn more about joints! Direct link: <a href=\"https:\/\/youtu.be\/DLxYDoN634c\">https:\/\/youtu.be\/DLxYDoN634c<\/a><\/figcaption><\/figure>\n<h2 style=\"text-align: justify\"><strong><a id=\"13-2\"><\/a>Part 2: Fibrous Joints<\/strong><\/h2>\n<p style=\"text-align: justify\">At a fibrous joint, the adjacent bones are directly connected to each other by fibrous connective tissue, and thus the bones do not have a joint cavity between them (Figure 4). The gap between the bones may be narrow or wide. There are three types of fibrous joints. A <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2822\"><strong>suture<\/strong><\/a> is the narrow fibrous joint found between most bones of the skull. At a syndesmosis joint, the bones are more widely separated but are held together by a narrow band of fibrous connective tissue called a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2735\">ligament<\/a> <\/strong>or a wide sheet of connective tissue called an interosseous membrane. This type of fibrous joint is found between the shaft regions of the long bones in the forearm and in the leg. Lastly, a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2891\">gomphosis<\/a> is the narrow fibrous joint between the roots of a tooth and the bony socket in the jaw into which the tooth fits.<\/p>\n<figure style=\"width: 1674px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/dcbiol110311092nded\/wp-content\/uploads\/sites\/750\/2019\/08\/image5-7.png\" alt=\"image\" width=\"1674\" height=\"734\" \/><figcaption class=\"wp-caption-text\"><strong>Figure 4. Fibrous Joints.<\/strong> Fibrous joints form strong connections between bones. (a) Sutures join most bones of the skull. (b) An interosseous membrane forms a syndesmosis between the radius and ulna bones of the forearm. (c) A gomphosis is a specialized fibrous joint that anchors a tooth to its socket in the jaw.<\/figcaption><\/figure>\n<h5 style=\"text-align: justify\"><strong><a id=\"13-2a\"><\/a>Suture<\/strong><\/h5>\n<p style=\"text-align: justify\">All the bones of the skull, except for the mandible, are joined to each other by a fibrous joint called a <strong>suture<\/strong>. The fibrous connective tissue found at a suture (\u201cto bind or sew\u201d) strongly unites the adjacent skull bones and thus helps to protect the brain and form the face. In adults, the skull bones are closely opposed, and fibrous connective tissue fills the narrow gap between the bones. The suture is frequently convoluted, forming a tight union that prevents most movement between the bones (Figure 4a). Thus, skull sutures are functionally classified as a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2887\">synarthrosis<\/a>, although some sutures may allow for slight movements between the cranial bones.<\/p>\n<p style=\"text-align: justify\">At some sutures, the connective tissue will ossify and be converted into bone, causing the adjacent bones to fuse to each other. Examples of fusions between cranial bones are found both early and late in life. At the time of birth, the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2825\">frontal<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2832\">maxillary<\/a> bones consist of right and left halves joined together by sutures, which disappear by the eighth year as the halves fuse together to form a single bone. Late in life, the sagittal, coronal, and lambdoid sutures of the skull will begin to ossify and fuse, causing the suture line to gradually disappear.<\/p>\n<h5 style=\"text-align: justify\"><strong><a id=\"13-2b\"><\/a>Syndesmosis<\/strong><\/h5>\n<p style=\"text-align: justify\">A <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2894\">syndesmosis<\/a> <\/strong>(\u201cfastened with a band\u201d) is a type of fibrous joint in which two parallel bones are united to each other by fibrous connective tissue. The gap between the bones may be narrow, with the bones joined by ligaments, or the gap may be wide and filled in by a broad sheet of connective tissue called an <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2893\">interosseous membrane<\/a><\/strong>.<\/p>\n<p style=\"text-align: justify\">In the forearm, the wide gap between the shaft portions of the radius and ulna bones are strongly united by an interosseous membrane (Figure 4b). Similarly, in the leg, the shafts of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2748\">tibia<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2749\">fibula<\/a> are also united by an interosseous membrane. In addition, at the distal tibiofibular joint, the articulating surfaces of the bones lack cartilage and the narrow gap between the bones is anchored by fibrous connective tissue and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2735\">ligaments<\/a> on both the anterior and posterior aspects of the joint. Together, the interosseous membrane and these ligaments form the tibiofibular syndesmosis.<\/p>\n<p style=\"text-align: justify\">The syndesmoses found in the forearm and leg serve to unite parallel bones and prevent their separation. However, a syndesmosis does not prevent all movement between the bones, and thus this type of fibrous joint is functionally classified as an <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2888\">amphiarthrosis<\/a>. In the leg, the syndesmosis between the tibia and fibula strongly unites the bones, allows for little movement, and firmly locks the talus bone in place between the tibia and fibula at the ankle joint. This provides strength and stability to the leg and ankle, which are important during weight bearing. In the forearm, the interosseous membrane is flexible enough to allow for rotation of the radius bone during forearm movements. Thus, in contrast to the stability provided by the tibiofibular syndesmosis, the flexibility of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2895\">antebrachial<\/a> interosseous membrane allows for the much greater mobility of the forearm.<\/p>\n<p style=\"text-align: justify\"><strong>Gomphosis:<\/strong> A <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2891\">gomphosis<\/a><\/strong> (\u201cfastened with bolts\u201d) is the specialized fibrous joint that anchors the root of a tooth into its bony socket within the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2832\">maxillary bone<\/a> (upper jaw) or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2820\">mandible bone<\/a> (lower jaw) of the skull. A gomphosis is also known as a peg-and-socket joint. Spanning between the bony walls of the socket and the root of the tooth are numerous short bands of dense connective tissue, each of which is called a <strong>periodontal ligament<\/strong> (see Figure 4c). Due to the immobility of a gomphosis, this type of joint is functionally classified as a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2887\">synarthrosis<\/a>.<\/p>\n<h2 style=\"text-align: justify\"><strong><a id=\"13-3\"><\/a>Part 3: Cartilaginous Joints<\/strong><\/h2>\n<p style=\"text-align: justify\">As the name indicates, at a cartilaginous joint, the adjacent bones are united by cartilage, a tough but flexible type of connective tissue.<\/p>\n<p style=\"text-align: justify\">These types of joints lack a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2883\">joint cavity<\/a> and involve bones that are joined together by either <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2321\">hyaline cartilage<\/a> or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2322\">fibrocartilage<\/a> (Figure 5). There are two types of cartilaginous joints. A synchondrosis is a cartilaginous joint where the bones are joined by hyaline cartilage. Also classified as a synchondrosis are places where bone is united to a cartilage structure, such as between the anterior end of a rib and the costal cartilage of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2816\">thoracic cage<\/a>. The second type of cartilaginous joint is a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2896\">symphysis<\/a>, where the bones are joined by fibrocartilage.<\/p>\n<figure style=\"width: 1668px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/dcbiol110311092nded\/wp-content\/uploads\/sites\/750\/2019\/08\/image7-7.png\" alt=\"image\" width=\"1668\" height=\"790\" \/><figcaption class=\"wp-caption-text\"><strong>Figure 5. Cartilaginous Joints.<\/strong> At cartilaginous joints, bones are united by hyaline cartilage to form a synchondrosis or by fibrocartilage to form a symphysis. (a) The hyaline cartilage of the epiphyseal plate (growth plate) forms a synchondrosis that unites the shaft (diaphysis) and end (epiphysis) of a long bone and allows the bone to grow in length. (b) The pubic portions of the right and left hip bones of the pelvis are joined together by fibrocartilage, forming the pubic symphysis.<\/figcaption><\/figure>\n<h5 style=\"text-align: justify\"><strong><a id=\"13-3a\"><\/a>Synchondrosis<\/strong><\/h5>\n<p style=\"text-align: justify\">A <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2897\">synchondrosis<\/a><\/strong> (\u201cjoined by cartilage\u201d) is a cartilaginous joint where bones are joined together by hyaline cartilage, or where bone is united to hyaline cartilage. A synchondrosis may be temporary or permanent. A temporary synchondrosis is the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2760\">epiphyseal plate<\/a> (growth plate) of a growing long bone. The epiphyseal plate is the region of growing hyaline cartilage that unites the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2756\">diaphysis<\/a> (shaft) of the bone to the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2757\">epiphysis<\/a> (end of the bone). Bone lengthening involves growth of the epiphyseal plate cartilage and its replacement by bone, which adds to the diaphysis. For many years during childhood growth, the rates of cartilage growth and bone formation are equal and thus the epiphyseal plate does not change in overall thickness as the bone lengthens. During the late teens and early 20s, growth of the cartilage slows and eventually stops. The epiphyseal plate is then completely replaced by bone, and the diaphysis and epiphysis portions of the bone fuse together to form a single adult bone. Once this occurs, bone lengthening ceases. For this reason, the epiphyseal plate is considered to be a temporary synchondrosis. Because cartilage is softer than bone tissue, injury to a growing long bone can damage the epiphyseal plate cartilage, thus stopping bone growth and preventing additional bone lengthening.<\/p>\n<p style=\"text-align: justify\">Growing layers of cartilage also form synchondroses that join together the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2867\">ilium<\/a>, <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2868\">ischium<\/a>, and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2869\">pubic<\/a> portions of the hip bone during childhood and adolescence. When body growth stops, the cartilage disappears and is replaced by bone, forming synostoses and fusing the bony components together into the single hip bone of the adult. Similarly, the sacral vertebrae fuse together to form the adult <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2817\">sacrum<\/a>.<\/p>\n<p style=\"text-align: justify\">Examples of permanent synchondroses are found in the thoracic cage. One example is the first sternocostal joint, where the first rib is anchored to the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2851\">manubrium<\/a> by its <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2853\">costal cartilage<\/a>. (The articulations of the remaining costal cartilages to the sternum are all synovial joints.) Additional synchondroses are formed where the anterior end of the other 11 ribs is joined to its costal cartilage. Unlike the temporary synchondroses of the epiphyseal plate, these permanent synchondroses retain their hyaline cartilage and thus do not ossify with age. Due to the lack of movement between the bone and cartilage, both temporary and permanent synchondroses are functionally classified as a synarthrosis.<\/p>\n<p style=\"text-align: justify\"><strong>Symphysis:<\/strong> A cartilaginous joint where the bones are joined by fibrocartilage is called a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2896\">symphysis<\/a> <\/strong>(\u201cgrowing together\u201d). Fibrocartilage is very strong because it contains numerous bundles of thick collagen fibers, thus giving it a much greater ability to resist pulling and bending forces when compared with hyaline cartilage. This gives symphyses the ability to strongly unite the adjacent bones but can still allow for limited movement to occur. Thus, a symphysis is functionally classified as an <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2888\">amphiarthrosis<\/a>.<\/p>\n<p style=\"text-align: justify\">The gap separating the bones at a symphysis may be narrow or wide. An example in which the gap between the bones is narrow is the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2871\">pubic symphysis<\/a>, where the pubic portions of the right and left hip bones of the pelvis are joined together by fibrocartilage across a narrow gap.<\/p>\n<p style=\"text-align: justify\">The intervertebral symphysis is a wide symphysis located between the bodies of adjacent vertebrae of the vertebral column. Here a thick pad of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2322\">fibrocartilage<\/a> called an intervertebral disc strongly unites the adjacent vertebrae by filling the gap between them. The width of the intervertebral symphysis is important because it allows for small movements between the adjacent vertebrae. In addition, the thick <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2833\">intervertebral disc<\/a> provides cushioning between the vertebrae, which is important when carrying heavy objects or during high-impact activities such as running or jumping.<\/p>\n<h2 style=\"text-align: justify\"><strong><a id=\"13-4\"><\/a>Part 4: Synovial Joints<\/strong><\/h2>\n<p style=\"text-align: justify\"><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2886\">Synovial joints<\/a> are the most common type of joint in the body (Figure 6). A key structural characteristic for a synovial joint that is not seen at fibrous or cartilaginous joints is the presence of a joint cavity. This fluid-filled space is the site at which the articulating surfaces of the bones contact each other. Also, unlike fibrous or cartilaginous joints, the articulating bone surfaces at a synovial joint are not directly connected to each other with fibrous connective tissue or cartilage. This gives the bones of a synovial joint the ability to move smoothly against each other, allowing for increased joint mobility.<\/p>\n<h5 style=\"text-align: justify\"><strong><a id=\"13-4a\"><\/a>Structural Features of Synovial Joints<\/strong><\/h5>\n<p style=\"text-align: justify\">Synovial joints are characterized by the presence of a joint cavity. The walls of this space are formed by the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2898\">articular capsule<\/a><\/strong>, a fibrous connective tissue structure that is attached to each bone just outside the area of the bone\u2019s articulating surface. The bones of the joint articulate with each other within the joint cavity.<\/p>\n<p style=\"text-align: justify\">Friction between the bones at a synovial joint is prevented by the presence of the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2763\">articular cartilage<\/a><\/strong>, a thin layer of <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2321\">hyaline cartilage<\/a> that covers the entire articulating surface of each bone. However, unlike at a cartilaginous joint, the articular cartilages of each bone are not continuous with each other. Instead, the articular cartilage acts like a Teflon\u00ae coating over the bone surface, allowing the articulating bones to move smoothly against each other without damaging the underlying bone tissue. Lining the inner surface of the articular capsule is a thin <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2899\">synovial membrane<\/a><\/strong>. The cells of this membrane secrete <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2107\">synovial fluid<\/a><\/strong> (synovia = \u201ca thick fluid\u201d), a thick, slimy fluid that provides lubrication to further reduce friction between the bones of the joint. This fluid also provides nourishment to the articular cartilage, which does not contain blood vessels. The ability of the bones to move smoothly against each other within the joint cavity, and the freedom of joint movement this provides, means that each synovial joint is functionally classified as a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2889\">diarthrosis<\/a>.<\/p>\n<figure style=\"width: 946px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/dcbiol110311092nded\/wp-content\/uploads\/sites\/750\/2019\/08\/image8-8.png\" alt=\"image\" width=\"946\" height=\"1027\" \/><figcaption class=\"wp-caption-text\"><strong>Figure 6. Synovial Joints.<\/strong> Synovial joints allow for smooth movements between the adjacent bones. The joint is surrounded by an articular capsule that defines a joint cavity filled with synovial fluid. The articulating surfaces of the bones are covered by a thin layer of articular cartilage. Ligaments support the joint by holding the bones together and resisting excess or abnormal joint motions.<\/figcaption><\/figure>\n<p style=\"text-align: justify\">Outside of their articulating surfaces, the bones are connected together by <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2735\">ligaments<\/a>,<\/strong> which are strong bands of fibrous connective tissue. These strengthen and support the joint by anchoring the bones together and preventing their separation. Ligaments allow for normal movements at a joint, but limit the range of these motions, thus preventing excessive or abnormal joint movements.<\/p>\n<p style=\"text-align: justify\">At many synovial joints, additional support is provided by the muscles and their tendons that act across the joint. A <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2736\">tendon<\/a><\/strong> is the dense connective tissue structure that attaches a muscle to bone. As forces acting on a joint increase, the body will automatically increase the overall strength of contraction of the muscles crossing that joint, thus allowing the muscle and its tendon to serve as a \u201cdynamic ligament\u201d to resist forces and support the joint. This type of indirect support by muscles is very important at the shoulder joint, for example, where the ligaments are relatively weak.<\/p>\n<h5 style=\"text-align: justify\"><strong><a id=\"13-4b\"><\/a>Additional Structures Associated with Synovial Joints<\/strong><\/h5>\n<p style=\"text-align: justify\">A few synovial joints of the body have a fibrocartilage structure located between the articulating bones. This is called an <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2900\">articular disc<\/a><\/strong>, which is generally small and oval-shaped, or a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2901\">meniscus<\/a><\/strong>, which is larger and C-shaped. These structures can serve several functions, depending on the specific joint. In some places, an articular disc may act to strongly unite the bones of the joint to each other. Examples of this include the articular discs found at the sternoclavicular joint or between the distal ends of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2747\">radius<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2745\">ulna<\/a> bones. At other synovial joints, the disc can provide shock absorption and cushioning between the bones, which is the function of each meniscus within the knee joint. Finally, an articular disc can serve to smooth the movements between the articulating bones, as seen at the temporomandibular joint. Some synovial joints also have a fat pad, which can serve as a cushion between the bones.<\/p>\n<p style=\"text-align: justify\">Additional structures located outside of a synovial joint serve to prevent friction between the bones of the joint and the overlying muscle tendons or skin. A <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2902\">bursa<\/a><\/strong> (plural = bursae) is a thin connective tissue sac filled with lubricating liquid. They are located in regions where skin, ligaments, muscles, or muscle tendons can rub against each other, usually near a body joint (Figure 7). Bursae reduce friction by separating the adjacent structures, preventing them from rubbing directly against each other.<\/p>\n<figure style=\"width: 1303px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/dcbiol110311092nded\/wp-content\/uploads\/sites\/750\/2019\/08\/image9-7.png\" alt=\"image\" width=\"1303\" height=\"1029\" \/><figcaption class=\"wp-caption-text\"><strong>Figure 7. Bursae.<\/strong> Bursae are fluid-filled sacs that serve to prevent friction between skin, muscle, or tendon and an underlying bone. Three major bursae and a fat pad are part of the complex joint that unites the femur and tibia of the leg.<\/figcaption><\/figure>\n<h5 style=\"text-align: justify\"><strong><a id=\"13-4c\"><\/a>Types of Synovial Joints<\/strong><\/h5>\n<p style=\"text-align: justify\">Synovial joints are subdivided based on the shapes of the articulating surfaces of the bones that form each joint. The six types of synovial joints are pivot, hinge, condyloid, saddle, plane (gliding), and ball-and socket-joints (Figure 8).<\/p>\n<p style=\"text-align: justify\"><strong>1. Pivot Joint:<\/strong> At a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2903\">pivot joint<\/a><\/strong>, a rounded portion of a bone is enclosed within a ring formed partially by the articulation with another bone and partially by a ligament (Figure 8a). The bone rotates within this ring. Since the rotation is around a single axis, pivot joints are functionally classified as a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2904\">uniaxial joint<\/a>. An example of a pivot joint is the atlantoaxial joint, found between the C1 (<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2848\">atlas<\/a>) and C2 (<a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2849\">axis<\/a>) vertebrae. Here, the upward projecting dens of the axis articulates with the inner aspect of the atlas, where it is held in place by a ligament. Rotation at this joint allows you to turn your head from side to side. A second pivot joint is found at the <strong>proximal radioulnar joint<\/strong>. Here, the head of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2747\">radius<\/a> is largely encircled by a ligament that holds it in place as it articulates with the radial notch of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2745\">ulna<\/a>. Rotation of the radius allows for forearm movements.<\/p>\n<p style=\"text-align: justify\"><strong>2. Hinge Joint:<\/strong> In a <strong>hinge joint<\/strong>, the convex end of one bone articulates with the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2912\">concave<\/a> end of the adjoining bone (Figure 8b). This type of joint allows only for angular movements &#8211; bending and straightening motions along a single axis &#8211; and thus hinge joints are functionally classified as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2904\">uniaxial joints<\/a>. A good example is the elbow joint, with the articulation between the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2746\">humerus<\/a> and the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2745\">ulna<\/a>. Other hinge joints of the body include the knee, ankle, and interphalangeal joints between the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2750\">phalanx<\/a> bones of the fingers and toes.<\/p>\n<p style=\"text-align: justify\"><strong>3. Condyloid Joint:<\/strong> At a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2910\">condyloid joint<\/a><\/strong> (ellipsoid joint), the shallow depression at the end of one bone articulates with a rounded structure from an adjacent bone or bones (Figure 8e). The knuckle (metacarpophalangeal) joints of the hand between the distal end of a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2744\">metacarpal<\/a> bone and the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2373\">proximal<\/a> <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2750\">phalanx<\/a> bone are condyloid joints. Another example is the radiocarpal joint of the wrist, between the shallow depression at the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2374\">distal<\/a> end of the radius bone and three of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2752\">carpal<\/a> bones. In this case, the articulation area has a more oval (elliptical) shape. Functionally, condyloid joints are <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2909\">biaxial joints<\/a> that allow for two planes of angular movement. One movement involves the bending and straightening of the fingers or the anterior-posterior movements of the hand. The second movement is a side-to-side movement, which allows you to spread your fingers apart and bring them together, or to move your hand in a medial-going or lateral-going direction.<\/p>\n<p style=\"text-align: justify\"><strong>4. Saddle Joint:<\/strong> At a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2907\"><strong>saddle joint<\/strong><\/a>, both of the articulating surfaces for the bones have a saddle shape, which is concave in one direction and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2908\">convex<\/a> in the other (Figure 8c). This allows the two bones to fit together like a rider sitting on a saddle. Saddle joints are functionally classified as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2909\">biaxial joints<\/a>. The primary example is the first carpometacarpal joint, between the trapezium (a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2752\">carpal<\/a> bone) and the first <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2744\">metacarpal<\/a> bone at the base of the thumb. This joint provides the thumb the ability for angular movement away from the palm of the hand along two planes. Thus, the thumb can move within the same plane as the palm of the hand, or it can jut out anteriorly, perpendicular to the palm. This movement of the first carpometacarpal joint is what gives humans their distinctive \u201copposable\u201d thumbs. The sternoclavicular joint is also classified as a saddle joint.<\/p>\n<p style=\"text-align: justify\"><strong>5. Plane Joint:<\/strong> At a <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2905\">plane joint<\/a><\/strong> (gliding joint), the articulating surfaces of the bones are flat or slightly curved and of approximately the same size, which allows for predominantly gliding movement where the bones slide back and forth against each other (Figure 8d). The motion at this type of joint is usually small and tightly constrained by surrounding ligaments. It is worth noting that based only on their shape, plane joints have the ability to allow multiple movements, including rotation. Thus, plane joints can be functionally classified as a <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2913\">multiaxial joint<\/a>. However, not all of these movements are available to every plane joint due to limitations placed on it by ligaments or neighboring bones. Thus, depending upon the specific joint of the body, a plane joint may exhibit only a single type of movement or several movements. Plane joints are found between the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2752\">carpal<\/a> bones (intercarpal joints) of the wrist or <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2753\">tarsal<\/a> bones (intertarsal joints) of the foot, between the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2786\">clavicle<\/a> and acromion of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2755\">scapula<\/a> (acromioclavicular joint), and between the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2359\">superior<\/a> and <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2360\">inferior<\/a> articular processes of adjacent vertebrae (zygapophysial joints).<\/p>\n<p style=\"text-align: justify\"><strong>6. Ball-and-Socket Joint:<\/strong> The joint with the greatest range of motion is the <strong><a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2906\">ball-and-socket joint<\/a><\/strong>. At these joints, the rounded head of one bone (the ball) fits into the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2912\">concave<\/a> articulation (the socket) of the adjacent bone (Figure 8f). The hip joint and the glenohumeral (shoulder) joint are the only ball-and-socket joints of the body. At the hip joint, the head of the femur articulates with the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2914\">acetabulum<\/a> of the hip bone, and at the shoulder joint, the head of the humerus articulates with the glenoid cavity of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2755\">scapula<\/a>.<\/p>\n<p style=\"text-align: justify\">Ball-and-socket joints are classified functionally as <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2913\">multiaxial joints<\/a>. The <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2379\">femur<\/a> and the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2746\">humerus<\/a> are able to effect angular movements in both anterior-posterior and medial-lateral directions and they can also rotate around their long axis. These multiaxial joints also allow for a complex movement called <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2915\">circumduction<\/a>. In this instance, the distal end of the bone moves in a circle while the proximal end remains relatively stationary. Circumduction of the arm and leg are possible at ball-and-socket joints.<\/p>\n<p style=\"text-align: justify\">The shallow socket formed by the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2863\">glenoid cavity<\/a> allows the shoulder joint an extensive range of motion. In contrast, the deep socket of the <a class=\"glossary-term\" aria-haspopup=\"dialog\" aria-describedby=\"definition\" href=\"#term_1658_2914\">acetabulum<\/a> and the strong supporting ligaments of the hip joint serve to constrain movements of the femur, reflecting the need for stability and weight-bearing ability at the hip.<\/p>\n<figure style=\"width: 878px\" class=\"wp-caption alignnone\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/pressbooks.bccampus.ca\/dcbiol110311092nded\/wp-content\/uploads\/sites\/750\/2019\/08\/image10-7.png\" alt=\"image\" width=\"878\" height=\"1038\" \/><figcaption class=\"wp-caption-text\"><strong>Figure 8. Types of Synovial Joints.<\/strong> The six types of synovial joints allow the body to move in a variety of ways. (a) Pivot joints allow for rotation around an axis, such as between the first and second cervical vertebrae, which allows for side-to-side rotation of the head. (b) The hinge joint of the elbow works like a door hinge. (c) The articulation between the trapezium carpal bone and the first metacarpal bone at the base of the thumb is a saddle joint. (d) Plane joints, such as those between the tarsal bones of the foot, allow for limited gliding movements between bones. (e) The radiocarpal joint of the wrist is a condyloid joint. (f) The hip and shoulder joints are the only ball-and-socket joints of the body.<\/figcaption><\/figure>\n<div class=\"textbox textbox--exercises\">\n<header class=\"textbox__header\">\n<p class=\"textbox__title\"><a id=\"P\"><\/a>Practice Questions<\/p>\n<\/header>\n<div class=\"textbox__content\">\n<p><strong>Part 1:<\/strong> Overview and Classification of Joints<\/p>\n<div id=\"h5p-49\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-49\" class=\"h5p-iframe\" data-content-id=\"49\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"13-1 264\"><\/iframe><\/div>\n<\/div>\n<div id=\"h5p-45\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-45\" class=\"h5p-iframe\" data-content-id=\"45\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"13-2 260\"><\/iframe><\/div>\n<\/div>\n<p><strong>Part 2: <\/strong>Fibrous Joints<\/p>\n<div id=\"h5p-47\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-47\" class=\"h5p-iframe\" data-content-id=\"47\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"13-3 262\"><\/iframe><\/div>\n<\/div>\n<div id=\"h5p-48\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-48\" class=\"h5p-iframe\" data-content-id=\"48\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"13-4 263\"><\/iframe><\/div>\n<\/div>\n<p><strong>Part 3:<\/strong> Cartilaginous Joints<\/p>\n<div id=\"h5p-51\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-51\" class=\"h5p-iframe\" data-content-id=\"51\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"13-5 266\"><\/iframe><\/div>\n<\/div>\n<div id=\"h5p-52\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-52\" class=\"h5p-iframe\" data-content-id=\"52\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"13-6 267\"><\/iframe><\/div>\n<\/div>\n<div id=\"h5p-53\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-53\" class=\"h5p-iframe\" data-content-id=\"53\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"13-7 268\"><\/iframe><\/div>\n<\/div>\n<p><strong>Part 4:<\/strong> Synovial Joints<\/p>\n<div id=\"h5p-46\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-46\" class=\"h5p-iframe\" data-content-id=\"46\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"13-8 261\"><\/iframe><\/div>\n<\/div>\n<div id=\"h5p-50\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-50\" class=\"h5p-iframe\" data-content-id=\"50\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"13-9 265\"><\/iframe><\/div>\n<\/div>\n<div id=\"h5p-54\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-54\" class=\"h5p-iframe\" data-content-id=\"54\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"13-10 269\"><\/iframe><\/div>\n<\/div>\n<div id=\"h5p-55\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-55\" class=\"h5p-iframe\" data-content-id=\"55\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"13-11 270\"><\/iframe><\/div>\n<\/div>\n<div id=\"h5p-56\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-56\" class=\"h5p-iframe\" data-content-id=\"56\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"13-11 271\"><\/iframe><\/div>\n<\/div>\n<div id=\"h5p-57\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-57\" class=\"h5p-iframe\" data-content-id=\"57\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"13-12 272\"><\/iframe><\/div>\n<\/div>\n<div id=\"h5p-58\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-58\" class=\"h5p-iframe\" data-content-id=\"58\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"13-13 273\"><\/iframe><\/div>\n<\/div>\n<div id=\"h5p-59\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-59\" class=\"h5p-iframe\" data-content-id=\"59\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"13-14 274\"><\/iframe><\/div>\n<\/div>\n<div id=\"h5p-60\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-60\" class=\"h5p-iframe\" data-content-id=\"60\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"13-15 275\"><\/iframe><\/div>\n<\/div>\n<div id=\"h5p-61\">\n<div class=\"h5p-iframe-wrapper\"><iframe id=\"h5p-iframe-61\" class=\"h5p-iframe\" data-content-id=\"61\" style=\"height:1px\" src=\"about:blank\" frameBorder=\"0\" scrolling=\"no\" title=\"13-16 276\"><\/iframe><\/div>\n<\/div>\n<\/div>\n<\/div>\n<p>&nbsp;<\/p>\n<\/div>\n<div class=\"glossary\"><span class=\"screen-reader-text\" id=\"definition\">definition<\/span><template id=\"term_1658_2883\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2883\"><div tabindex=\"-1\"><p>Space enclosed by the articular capsule of a synovial joint that is filled with synovial fluid and contains the articulating surfaces of the adjacent bones.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2884\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2884\"><div tabindex=\"-1\"><p>Joint where the articulating areas of the adjacent bones are connected by fibrous connective tissue.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2885\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2885\"><div tabindex=\"-1\"><p>Joint at which the bones are united by hyaline cartilage (synchondrosis) or fibrocartilage (symphysis).<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2886\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2886\"><div tabindex=\"-1\"><p>Joint at which the articulating surfaces of the bones are located within a joint cavity formed by an articular capsule.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2887\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2887\"><div tabindex=\"-1\"><p>Immobile or nearly immobile joint.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2888\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2888\"><div tabindex=\"-1\"><p>Slightly mobile joint.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2889\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2889\"><div tabindex=\"-1\"><p>Freely mobile joint.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2322\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2322\"><div tabindex=\"-1\"><p>Tough form of cartilage, made of thick bundles of collagen fibers embedded in chondroitin sulfate ground substance.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2833\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2833\"><div tabindex=\"-1\"><p>Structure located between the bodies of adjacent vertebrae that strongly joins the vertebrae; provides padding, weight bearing ability, and enables vertebral column movements.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2871\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2871\"><div tabindex=\"-1\"><p>Joint formed by the articulation between the pubic bodies of the right and left hip bones.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2890\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2890\"><div tabindex=\"-1\"><p>Type of diarthrosis; a joint that allows for movements within three planes (three axes).<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2822\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2822\"><div tabindex=\"-1\"><p>Fibrous joint that connects the bones of the skull (except the mandible); an immobile joint (synarthrosis).<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2735\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2735\"><div tabindex=\"-1\"><p>Strong connective tissue bands that hold the bones at a moveable joint together.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2891\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2891\"><div tabindex=\"-1\"><p>Type of fibrous joint in which the root of a tooth is anchored into its bony jaw socket by strong periodontal ligaments.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2825\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2825\"><div tabindex=\"-1\"><p>Unpaired bone that forms forehead, roof of orbit, and floor of anterior cranial fossa.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2832\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2832\"><div tabindex=\"-1\"><p>(Also, maxilla) paired bones that form the upper jaw and anterior portion of the hard palate.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2894\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2894\"><div tabindex=\"-1\"><p>Type of fibrous joint in which two separated, parallel bones are connected by an interosseous membrane.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2893\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2893\"><div tabindex=\"-1\"><p>Wide sheet of fibrous connective tissue that fills the gap between two parallel bones, forming a syndesmosis; found between the radius and ulna of the forearm and between the tibia and fibula of the leg.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2748\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2748\"><div tabindex=\"-1\"><p>Shin bone; the large, weight-bearing bone located on the medial side of the leg.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2749\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2749\"><div tabindex=\"-1\"><p>Thin, non-weight-bearing bone found on the lateral side of the leg.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2895\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2895\"><div tabindex=\"-1\"><p>Relating to the forearm.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2820\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2820\"><div tabindex=\"-1\"><p>Unpaired bone that forms the lower jaw bone; the only moveable bone of the skull.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2321\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2321\"><div tabindex=\"-1\"><p>Most common type of cartilage, smooth and made of short collagen fibers embedded in a chondroitin sulfate ground substance.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2816\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2816\"><div tabindex=\"-1\"><p>Consists of 12 pairs of ribs and sternum.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2896\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2896\"><div tabindex=\"-1\"><p>Type of cartilaginous joint where the bones are joined by fibrocartilage.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2897\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2897\"><div tabindex=\"-1\"><p>Type of cartilaginous joint where the bones are joined by hyaline cartilage.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2760\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2760\"><div tabindex=\"-1\"><p>(Also, growth plate) sheet of hyaline cartilage in the metaphysis of an immature bone; replaced by bone tissue as the organ grows in length.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2756\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2756\"><div tabindex=\"-1\"><p>Tubular shaft that runs between the proximal and distal ends of a long bone.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2757\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2757\"><div tabindex=\"-1\"><p>Wide section at each end of a long bone; filled with spongy bone and red marrow.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2867\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2867\"><div tabindex=\"-1\"><p>Superior portion of the hip bone.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2868\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2868\"><div tabindex=\"-1\"><p>Superior portion of the hip bone.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2869\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2869\"><div tabindex=\"-1\"><p>Anterior portion of the hip bone.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2817\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2817\"><div tabindex=\"-1\"><p>Single bone located near the inferior end of the adult vertebral column that is formed by the fusion of five sacral vertebrae; forms the posterior portion of the pelvis.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2851\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2851\"><div tabindex=\"-1\"><p>Expanded, superior portion of the sternum.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2853\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2853\"><div tabindex=\"-1\"><p>Hyaline cartilage structure attached to the anterior end of each rib that provides for either direct or indirect attachment of most ribs to the sternum.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2898\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2898\"><div tabindex=\"-1\"><p>Connective tissue structure that encloses the joint cavity of a synovial joint.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2763\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2763\"><div tabindex=\"-1\"><p>Thin layer of cartilage covering an epiphysis; reduces friction and acts as a shock absorber.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2899\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2899\"><div tabindex=\"-1\"><p>Thin layer that lines the inner surface of the joint cavity at a synovial joint; produces the synovial fluid.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2107\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2107\"><div tabindex=\"-1\"><p>Thick, lubricating fluid that fills the interior of a synovial joint.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2736\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2736\"><div tabindex=\"-1\"><p>Dense regular connective tissue that attaches skeletal muscle to bone.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2900\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2900\"><div tabindex=\"-1\"><p>Meniscus; a fibrocartilage structure found between the bones of some synovial joints; provides padding or smooths movements between the bones; strongly unites the bones together.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2901\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2901\"><div tabindex=\"-1\"><p>See <strong>articular disc<\/strong><\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2747\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2747\"><div tabindex=\"-1\"><p>Bone located on the lateral side of the forearm.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2745\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2745\"><div tabindex=\"-1\"><p>Bone located on the medial side of the forearm.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2902\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2902\"><div tabindex=\"-1\"><p>Connective tissue sac containing lubricating fluid that prevents friction between adjacent structures, such as skin and bone, tendons and bone, or between muscles.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2903\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2903\"><div tabindex=\"-1\"><p>Synovial joint at which the rounded portion of a bone rotates within a ring formed by a ligament and an articulating bone; functionally classified as uniaxial joint.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2904\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2904\"><div tabindex=\"-1\"><p>Type of diarthrosis; joint that allows for motion within only one plane (one axis).<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2848\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2848\"><div tabindex=\"-1\"><p>First cervical (C1) vertebra.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2849\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2849\"><div tabindex=\"-1\"><p>Second cervical (C2) vertebra.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2912\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2912\"><div tabindex=\"-1\"><p>Hollowed or rounded inward, like the inside of a bowl. Opposite of convex.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2746\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2746\"><div tabindex=\"-1\"><p>Single bone of the upper arm.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2750\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2750\"><div tabindex=\"-1\"><p>(plural = phalanges) one of the bones that form the fingers or toes.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2910\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2910\"><div tabindex=\"-1\"><p>Synovial joint in which the shallow depression at the end of one bone receives a rounded end from a second bone or a rounded structure formed by two bones; found at the metacarpophalangeal joints of the fingers or the radiocarpal joint of the wrist; functionally classified as a biaxial joint.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2744\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2744\"><div tabindex=\"-1\"><p>One of the five long bones that form the palm of the hand; numbered 1\u20135, starting on the lateral (thumb) side of the hand.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2373\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2373\"><div tabindex=\"-1\"><p>Describes a position in a limb that is nearer to the point of attachment or the trunk of the body.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2374\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2374\"><div tabindex=\"-1\"><p>Describes a position in a limb that is farther from the point of attachment or the trunk of the body.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2752\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2752\"><div tabindex=\"-1\"><p>One of the eight small bones that form the wrist and base of the hand; these are grouped as a proximal row consisting of (from lateral to medial) the scaphoid, lunate, triquetrum, and pisiform bones, and a distal row containing (from lateral to medial) the trapezium, trapezoid, capitate, and hamate bones.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2909\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2909\"><div tabindex=\"-1\"><p>Type of diarthrosis; a joint that allows for movements within two planes (two axes).<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2907\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2907\"><div tabindex=\"-1\"><p>Synovial joint in which the articulating ends of both bones are convex and concave in shape, such as at the first carpometacarpal joint at the base of the thumb; functionally classified as a biaxial joint.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2908\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2908\"><div tabindex=\"-1\"><p>Having an outline or surface curved like the outside of a circle or sphere.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2905\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2905\"><div tabindex=\"-1\"><p>Synovial joint formed between the flattened articulating surfaces of adjacent bones; functionally classified as a multiaxial joint.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2913\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2913\"><div tabindex=\"-1\"><p>Type of diarthrosis; a joint that allows for movements within three planes (three axes).<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2753\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2753\"><div tabindex=\"-1\"><p>One of the seven bones that make up the posterior foot; includes the calcaneus, talus, navicular, cuboid, medial cuneiform, intermediate cuneiform, and lateral cuneiform bones.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2786\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2786\"><div tabindex=\"-1\"><p>Collarbone; elongated bone that articulates with the manubrium of the sternum medially and the acromion of the scapula laterally.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2755\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2755\"><div tabindex=\"-1\"><p>Shoulder blade bone located on the posterior side of the shoulder.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2359\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2359\"><div tabindex=\"-1\"><p>Describes a position above or higher than another part of the body proper; also referred to as cranial.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2360\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2360\"><div tabindex=\"-1\"><p>Describes a position below or lower than another part of the body proper; near or toward the tail (in humans, the coccyx, or lowest part of the spinal column); also referred to as caudal.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2906\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2906\"><div tabindex=\"-1\"><p>Synovial joint at which the rounded portion of a bone rotates within a ring formed by a ligament and an articulating bone; functionally classified as uniaxial joint.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2914\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2914\"><div tabindex=\"-1\"><p>Large, cup-shaped cavity located on the lateral side of the hip bone; formed by the junction of the ilium, pubis, and ischium portions of the hip bone.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2379\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2379\"><div tabindex=\"-1\"><p>Thigh bone; the single bone of the thigh.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2915\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2915\"><div tabindex=\"-1\"><p>Circular motion of the arm, thigh, hand, thumb, or finger that is produced by the sequential combination of flexion, abduction, extension, and adduction.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><template id=\"term_1658_2863\"><div class=\"glossary__definition\" role=\"dialog\" data-id=\"term_1658_2863\"><div tabindex=\"-1\"><p>(Also, glenoid fossa) shallow depression located on the lateral scapula, between the superior and lateral borders.<\/p>\n<\/div><button><span aria-hidden=\"true\">&times;<\/span><span class=\"screen-reader-text\">Close definition<\/span><\/button><\/div><\/template><\/div>","protected":false},"author":10,"menu_order":3,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-1658","chapter","type-chapter","status-publish","hentry"],"part":337,"_links":{"self":[{"href":"https:\/\/pressbooks.bccampus.ca\/dcbiol110311092nded\/wp-json\/pressbooks\/v2\/chapters\/1658","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pressbooks.bccampus.ca\/dcbiol110311092nded\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/pressbooks.bccampus.ca\/dcbiol110311092nded\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/dcbiol110311092nded\/wp-json\/wp\/v2\/users\/10"}],"version-history":[{"count":23,"href":"https:\/\/pressbooks.bccampus.ca\/dcbiol110311092nded\/wp-json\/pressbooks\/v2\/chapters\/1658\/revisions"}],"predecessor-version":[{"id":3210,"href":"https:\/\/pressbooks.bccampus.ca\/dcbiol110311092nded\/wp-json\/pressbooks\/v2\/chapters\/1658\/revisions\/3210"}],"part":[{"href":"https:\/\/pressbooks.bccampus.ca\/dcbiol110311092nded\/wp-json\/pressbooks\/v2\/parts\/337"}],"metadata":[{"href":"https:\/\/pressbooks.bccampus.ca\/dcbiol110311092nded\/wp-json\/pressbooks\/v2\/chapters\/1658\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/pressbooks.bccampus.ca\/dcbiol110311092nded\/wp-json\/wp\/v2\/media?parent=1658"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/dcbiol110311092nded\/wp-json\/pressbooks\/v2\/chapter-type?post=1658"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/dcbiol110311092nded\/wp-json\/wp\/v2\/contributor?post=1658"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/dcbiol110311092nded\/wp-json\/wp\/v2\/license?post=1658"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}