The Erector Spinae Group
The Erector Spinae group consist of Illiocostalis, Longissimus, and Spinalis (Lateral to medial). The main action of the Erector Spinae group is extension of the back.
Posterior Abdomen: Location of Fourth Lumbar Vertebrae
The human body can be used to help study and develop a stronger understanding of anatomy. Surface anatomy can be used to help form a deeper knowledge of how anatomy lies beneath the skin. Looking at the posterior aspect of the lumbar spine, specific techniques can be used to palpate the lumbar vertebrae. A trick can be used by physiotherapists and massage therapists to identify the location of L4. Looking at the photo below, start by locating the left and right iliac crests and walking your fingers horizontally until you reach the vertebral spine. Here, you have the fourth vertebrae of the lumbar vertebrae. Found by palpating, you can feel the spinous processes of the L4, this feels like a small, hard bump in line with the spine. If you then walk your fingers superior, you can count the spinous processes of L3, L2 and L1. If you walk your fingers inferiorly from the land mark of L4, you can than feel L5. Land marking regions like these can be done on oneself or a partner.