29 Dura Mater “Tough Mother” Thick, leathery outer covering Adheres to inner surface of skullSupport, and forms sinus system (veinous drainage)Pain sensitiveHas own blood supply -- Middle meningeal artery
30 Arachnoid Spongy/fibrous layer between the dura and pia Collagenous connective tissueKeep brain suspended in meningesSubarachnoid spaceContains CSF
31 Pia Mater Innermost layer Adheres almost indistinguishably to cortical surface, including sulci and gyriDifficult to see grossly or remove
38 Also called dural septa Dural ReflectionsAlso called dural septaIn certain places, the dura doubles on itself and forms a division or partition between parts of the brainFalx cerebriTentorium cerebelli
39 Falx CerebriExtends down the longitudinal fissure, between the cerebral hemispheresForms the triangular-shaped superior sagittal sinus superiorly
42 Tentorium CerebelliExtends inward between the cerebellum and occipital lobesForms a “soft top” for the posterior cranial fossaBrain stem passes through tentorial notchForms the transverse sinus posteriorly
50 Bleeds Subdural Hematoma Rupture of bridging veins from surface of cortex to veinous sinuses (e.g., superior sagittal sinus)Accumulates more slowly (veins)Still results in mass effect and compression of the brainOlder people particularly susceptible. Why?
53 Bleeds Subarachnoid Hemorrhage Rupture of cerebral vein or artery Bleeding into the subarachnoid spaceBlood hugs the surface of the brain (i.e., within the subarachnoid space). No mass effectCan block flow of CSF and result in hydrocephalus