{"id":5429,"date":"2025-12-09T12:33:25","date_gmt":"2025-12-09T17:33:25","guid":{"rendered":"https:\/\/pressbooks.bccampus.ca\/pathophysiology\/?post_type=chapter&p=5429"},"modified":"2025-12-09T21:45:57","modified_gmt":"2025-12-10T02:45:57","slug":"brain-lesions-in-relation-to-the-anatomy-of-the-meninges","status":"web-only","type":"chapter","link":"https:\/\/pressbooks.bccampus.ca\/pathophysiology\/chapter\/brain-lesions-in-relation-to-the-anatomy-of-the-meninges\/","title":{"raw":"11p2 Brain Lesions in Relation to the Anatomy of the Meninges","rendered":"11p2 Brain Lesions in Relation to the Anatomy of the Meninges"},"content":{"raw":"

Anatomy of the Meninges<\/strong><\/h1>\r\nLayers of Protective Covering<\/strong>\r\n
    \r\n \t
  • Skull<\/strong>: Outer protective case.<\/li>\r\n \t
  • Periosteum<\/strong>: Dense connective tissue lining the skull.<\/li>\r\n \t
  • Meninges<\/strong>: Three layers:\r\n
      \r\n \t
    1. Dura mater<\/strong>:\r\n
        \r\n \t
      • Tough,\u00a0dense irregular connective tissue<\/strong>.<\/li>\r\n \t
      • 3 Dural Folds (sheets of dura mater meningeal layer)<\/strong>:\r\n
          \r\n \t
        • Falx cerebri<\/strong>: Sickle-shaped, divides the two cerebral hemispheres.<\/li>\r\n \t
        • Tentorium cerebelli<\/strong>: Separates cerebrum and cerebellum.<\/li>\r\n \t
        • Falx cerebelli<\/strong>: Divides the right and left cerebellar hemispheres.<\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>\r\n<\/li>\r\n \t
        • Arachnoid mater<\/strong>:\r\n
            \r\n \t
          • Spider-web-like<\/strong>\u00a0trabeculae connecting to pia mater.<\/li>\r\n<\/ul>\r\n<\/li>\r\n \t
          • Pia mater<\/strong>:\r\n
              \r\n \t
            • Innermost, closely adheres to brain tissue.<\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ol>\r\n<\/li>\r\n<\/ul>\r\n

              Function of Dural Meningeal Folds<\/strong><\/h1>\r\n
                \r\n \t
              • Prevent excessive movement<\/strong>\u00a0of the brain.<\/li>\r\n \t
              • Support blood vessels<\/strong>\u00a0and\u00a0prevent shearing injuries<\/strong>.<\/li>\r\n<\/ul>\r\nSignificance of the Tentorium Cerebelli<\/strong>\r\n
                  \r\n \t
                • Acts as a\u00a0divider<\/strong>:\r\n
                    \r\n \t
                  • Supratentorial region<\/strong>: Above the tentorium.<\/li>\r\n \t
                  • Infratentorial region<\/strong>: Below the tentorium, including the cerebellum and brainstem.<\/li>\r\n<\/ul>\r\n<\/li>\r\n \t
                  • Lesion location<\/strong>:\r\n
                      \r\n \t
                    • Supratentorial<\/strong>: Effects localized to cerebral cortex.<\/strong><\/li>\r\n \t
                    • Infratentorial<\/strong>: Affects cerebellum<\/strong> and\/or brainstem<\/strong>\r\n
                        \r\n \t
                      • Cerebellar lesions:<\/strong> result in loss of coordination, balance, and\/or posture<\/li>\r\n \t
                      • Brainstem lesions:<\/strong> affect vital functions, risk of coma or death<\/strong>.<\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>\r\n

                        Location of Brain Lesions: Supra- and Infratentorial<\/strong><\/h1>\r\nDefinitions<\/strong>\r\n
                          \r\n \t
                        • Supratentorial lesion<\/strong>:\r\n
                            \r\n \t
                          • Located\u00a0above<\/strong> the tentorium cerebelli (dural fold of the meningeal dura mater).<\/li>\r\n \t
                          • Usually affects\u00a0cerebral cortex<\/strong>.<\/li>\r\n \t
                          • Causes\u00a0specific neurological deficits<\/strong>\u00a0depending on lesion site.<\/li>\r\n<\/ul>\r\n<\/li>\r\n \t
                          • Infratentorial lesion<\/strong>:\r\n
                              \r\n \t
                            • Located\u00a0below<\/strong> the tentorium cerebelli (dural fold of the meningeal dura mater).<\/li>\r\n \t
                            • Involves\u00a0cerebellum<\/strong>\u00a0or\u00a0brainstem<\/strong>.<\/li>\r\n \t
                            • More dangerous because it affects\u00a0vital centers<\/strong>\u00a0controlling\u00a0heart rate<\/strong>,\u00a0breathing<\/strong>, and\u00a0consciousness<\/strong>.<\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>\r\nImplications<\/strong>\r\n
                                \r\n \t
                              • Growth or bleeding<\/strong>\u00a0in either area can\u00a0spread<\/strong>\u00a0and cause widespread damage.<\/li>\r\n \t
                              • Damage to\u00a0brainstem<\/strong>\u00a0(midbrain, pons, medulla):\r\n
                                  \r\n \t
                                • Critical\u00a0vital functions<\/strong>\u00a0are controlled here.<\/li>\r\n \t
                                • Damage can lead to\u00a0coma<\/strong>\u00a0or\u00a0death<\/strong>.<\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>\r\n

                                  Effects of Damage Based on Location<\/strong><\/h1>\r\n
                                    \r\n \t
                                  • Damage\u00a0above<\/strong>\u00a0the tentorium:\r\n
                                      \r\n \t
                                    • Usually\u00a0discrete<\/strong>\u00a0and localized.<\/li>\r\n \t
                                    • Cause\u00a0specific neurological deficits<\/strong>.<\/li>\r\n<\/ul>\r\n<\/li>\r\n \t
                                    • Damage\u00a0below<\/strong>\u00a0the tentorium:\r\n
                                        \r\n \t
                                      • Affects\u00a0brainstem<\/strong>, which controls:\r\n
                                          \r\n \t
                                        • Heart rate, Force of Contraction<\/strong>.<\/li>\r\n \t
                                        • Vasomotor control<\/strong> of vasodilation and vasoconstriction<\/li>\r\n \t
                                        • Breathing<\/strong>.<\/li>\r\n \t
                                        • Consciousness<\/strong>\u00a0(reticular activating system).<\/li>\r\n<\/ul>\r\n<\/li>\r\n \t
                                        • In addition to ascending<\/strong> and descending<\/strong> tracts that pass through the brainstem carrying sensory<\/strong> and motor<\/strong> information between the central nervous system (CNS) and peripheral nervous system (PNS)<\/li>\r\n \t
                                        • Can lead to\u00a0widespread impairment<\/strong>\u00a0and\u00a0coma<\/strong>.<\/li>\r\n<\/ul>\r\n<\/li>\r\n<\/ul>\r\n

                                          Summary<\/strong><\/h1>\r\n
                                            \r\n \t
                                          • The location of brain lesions determines severity and symptoms.<\/li>\r\n \t
                                          • The\u00a0tentorium cerebelli<\/strong>\u00a0divides the brain into critical regions with different risks.<\/li>\r\n \t
                                          • Damage to\u00a0brainstem<\/strong>\u00a0is particularly serious due to its role in vital functions.<\/li>\r\n<\/ul>","rendered":"

                                            Anatomy of the Meninges<\/strong><\/h1>\n

                                            Layers of Protective Covering<\/strong><\/p>\n

                                              \n
                                            • Skull<\/strong>: Outer protective case.<\/li>\n
                                            • Periosteum<\/strong>: Dense connective tissue lining the skull.<\/li>\n
                                            • Meninges<\/strong>: Three layers:\n
                                                \n
                                              1. Dura mater<\/strong>:\n
                                                  \n
                                                • Tough,\u00a0dense irregular connective tissue<\/strong>.<\/li>\n
                                                • 3 Dural Folds (sheets of dura mater meningeal layer)<\/strong>:\n
                                                    \n
                                                  • Falx cerebri<\/strong>: Sickle-shaped, divides the two cerebral hemispheres.<\/li>\n
                                                  • Tentorium cerebelli<\/strong>: Separates cerebrum and cerebellum.<\/li>\n
                                                  • Falx cerebelli<\/strong>: Divides the right and left cerebellar hemispheres.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n
                                                  • Arachnoid mater<\/strong>:\n
                                                      \n
                                                    • Spider-web-like<\/strong>\u00a0trabeculae connecting to pia mater.<\/li>\n<\/ul>\n<\/li>\n
                                                    • Pia mater<\/strong>:\n
                                                        \n
                                                      • Innermost, closely adheres to brain tissue.<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n<\/li>\n<\/ul>\n

                                                        Function of Dural Meningeal Folds<\/strong><\/h1>\n
                                                          \n
                                                        • Prevent excessive movement<\/strong>\u00a0of the brain.<\/li>\n
                                                        • Support blood vessels<\/strong>\u00a0and\u00a0prevent shearing injuries<\/strong>.<\/li>\n<\/ul>\n

                                                          Significance of the Tentorium Cerebelli<\/strong><\/p>\n

                                                            \n
                                                          • Acts as a\u00a0divider<\/strong>:\n
                                                              \n
                                                            • Supratentorial region<\/strong>: Above the tentorium.<\/li>\n
                                                            • Infratentorial region<\/strong>: Below the tentorium, including the cerebellum and brainstem.<\/li>\n<\/ul>\n<\/li>\n
                                                            • Lesion location<\/strong>:\n
                                                                \n
                                                              • Supratentorial<\/strong>: Effects localized to cerebral cortex.<\/strong><\/li>\n
                                                              • Infratentorial<\/strong>: Affects cerebellum<\/strong> and\/or brainstem<\/strong>\n
                                                                  \n
                                                                • Cerebellar lesions:<\/strong> result in loss of coordination, balance, and\/or posture<\/li>\n
                                                                • Brainstem lesions:<\/strong> affect vital functions, risk of coma or death<\/strong>.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n

                                                                  Location of Brain Lesions: Supra- and Infratentorial<\/strong><\/h1>\n

                                                                  Definitions<\/strong><\/p>\n

                                                                    \n
                                                                  • Supratentorial lesion<\/strong>:\n
                                                                      \n
                                                                    • Located\u00a0above<\/strong> the tentorium cerebelli (dural fold of the meningeal dura mater).<\/li>\n
                                                                    • Usually affects\u00a0cerebral cortex<\/strong>.<\/li>\n
                                                                    • Causes\u00a0specific neurological deficits<\/strong>\u00a0depending on lesion site.<\/li>\n<\/ul>\n<\/li>\n
                                                                    • Infratentorial lesion<\/strong>:\n
                                                                        \n
                                                                      • Located\u00a0below<\/strong> the tentorium cerebelli (dural fold of the meningeal dura mater).<\/li>\n
                                                                      • Involves\u00a0cerebellum<\/strong>\u00a0or\u00a0brainstem<\/strong>.<\/li>\n
                                                                      • More dangerous because it affects\u00a0vital centers<\/strong>\u00a0controlling\u00a0heart rate<\/strong>,\u00a0breathing<\/strong>, and\u00a0consciousness<\/strong>.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n

                                                                        Implications<\/strong><\/p>\n

                                                                          \n
                                                                        • Growth or bleeding<\/strong>\u00a0in either area can\u00a0spread<\/strong>\u00a0and cause widespread damage.<\/li>\n
                                                                        • Damage to\u00a0brainstem<\/strong>\u00a0(midbrain, pons, medulla):\n
                                                                            \n
                                                                          • Critical\u00a0vital functions<\/strong>\u00a0are controlled here.<\/li>\n
                                                                          • Damage can lead to\u00a0coma<\/strong>\u00a0or\u00a0death<\/strong>.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n

                                                                            Effects of Damage Based on Location<\/strong><\/h1>\n
                                                                              \n
                                                                            • Damage\u00a0above<\/strong>\u00a0the tentorium:\n
                                                                                \n
                                                                              • Usually\u00a0discrete<\/strong>\u00a0and localized.<\/li>\n
                                                                              • Cause\u00a0specific neurological deficits<\/strong>.<\/li>\n<\/ul>\n<\/li>\n
                                                                              • Damage\u00a0below<\/strong>\u00a0the tentorium:\n
                                                                                  \n
                                                                                • Affects\u00a0brainstem<\/strong>, which controls:\n
                                                                                    \n
                                                                                  • Heart rate, Force of Contraction<\/strong>.<\/li>\n
                                                                                  • Vasomotor control<\/strong> of vasodilation and vasoconstriction<\/li>\n
                                                                                  • Breathing<\/strong>.<\/li>\n
                                                                                  • Consciousness<\/strong>\u00a0(reticular activating system).<\/li>\n<\/ul>\n<\/li>\n
                                                                                  • In addition to ascending<\/strong> and descending<\/strong> tracts that pass through the brainstem carrying sensory<\/strong> and motor<\/strong> information between the central nervous system (CNS) and peripheral nervous system (PNS)<\/li>\n
                                                                                  • Can lead to\u00a0widespread impairment<\/strong>\u00a0and\u00a0coma<\/strong>.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n

                                                                                    Summary<\/strong><\/h1>\n
                                                                                      \n
                                                                                    • The location of brain lesions determines severity and symptoms.<\/li>\n
                                                                                    • The\u00a0tentorium cerebelli<\/strong>\u00a0divides the brain into critical regions with different risks.<\/li>\n
                                                                                    • Damage to\u00a0brainstem<\/strong>\u00a0is particularly serious due to its role in vital functions.<\/li>\n<\/ul>\n","protected":false},"author":1370,"menu_order":9,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":["zoe-soon"],"pb_section_license":"cc-by-nc-sa"},"chapter-type":[],"contributor":[60],"license":[57],"class_list":["post-5429","chapter","type-chapter","status-web-only","hentry","contributor-zoe-soon","license-cc-by-nc-sa"],"part":76,"_links":{"self":[{"href":"https:\/\/pressbooks.bccampus.ca\/pathophysiology\/wp-json\/pressbooks\/v2\/chapters\/5429","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pressbooks.bccampus.ca\/pathophysiology\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/pressbooks.bccampus.ca\/pathophysiology\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/pathophysiology\/wp-json\/wp\/v2\/users\/1370"}],"version-history":[{"count":6,"href":"https:\/\/pressbooks.bccampus.ca\/pathophysiology\/wp-json\/pressbooks\/v2\/chapters\/5429\/revisions"}],"predecessor-version":[{"id":5538,"href":"https:\/\/pressbooks.bccampus.ca\/pathophysiology\/wp-json\/pressbooks\/v2\/chapters\/5429\/revisions\/5538"}],"part":[{"href":"https:\/\/pressbooks.bccampus.ca\/pathophysiology\/wp-json\/pressbooks\/v2\/parts\/76"}],"metadata":[{"href":"https:\/\/pressbooks.bccampus.ca\/pathophysiology\/wp-json\/pressbooks\/v2\/chapters\/5429\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/pressbooks.bccampus.ca\/pathophysiology\/wp-json\/wp\/v2\/media?parent=5429"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/pathophysiology\/wp-json\/pressbooks\/v2\/chapter-type?post=5429"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/pathophysiology\/wp-json\/wp\/v2\/contributor?post=5429"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/pressbooks.bccampus.ca\/pathophysiology\/wp-json\/wp\/v2\/license?post=5429"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}