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Gross Brain Overview: Part I Basic Neuroscience James H. Baños, Ph.D. Overview Anatomical Directions Cranial Fossa Meninges Pathology of the Cranial Fossa & Meninges Anatomical Directions Dorsal fin Anatomical Directions Dorsal fin Anatomical Directions Dorsal fin Anatomical Directions Dorsal Ventral Anatomical Directions Dorsal Caudal Caudus = tail Rostral Rostrum = Stage or speaking platform Ventral Anatomical Directions Dorsal-ventral and rostral-caudal are with respect to the neuraxis Dorsal Rostral Caudal Ventral Anatomical Directions But wait……we evolved Anatomical Directions But wait……we evolved… Rostral Dorsal Caudal Ventral Dorsal Rostral Caudal Ventral Ventral Dorsal Caudal Anatomical Directions Rostral Caudal Caudal Anatomical Directions Dorsal Ventral Dorsal Ventral Anatomical Directions Anterior-posterior and superior-inferior are in 3-D space And do not respect the neuraxis. Anterior Superior Posterior Superior Inferior Anterior Posterior Inferior Anatomical Directions Medial-lateral can also respect either the midline, or some other reference point Lateral A B Medial Anatomical Directions Just to keep it interesting: Mesial = Medial Anatomical Directions Proximal Distal Ipsilateral vs. Contralateral Ipsilateral -- On the same side, with respect to a reference point Contralateral -- Opposite side, with respect to a reference point Anatomical Planes Sagittal Plane Horizontal/axial Plane Coronal Plane Transverse Section Coronal Plane Corona = crown….but think Statue of Liberty Sagittal Plane Sagittal MRI Mid-sagittal plane Horizontal Plane AKA: Axial plane CT plane Cranial Fossa Cranial Fossa Distinct areas of the skull base Contain and support various parts of the brain Contact point for the meninges Cranial Fossa Anterior cranial fossa -- frontal lobes Middle cranial fossa -- Temporal lobes Posterior cranial fossa -- Cerebellum and brain stem Cranial fossa contain lumen, or holes for cranial nerves, arterial supply, and venous drainage Meninges Meninges Three layers covering the brain Dura mater Arachnoid Pia mater Support, protection Contain circulating CSF that supports the brain Meninges Dura Mater “Tough Mother” Thick, leathery outer covering Adheres to inner surface of skull Support, and forms sinus system (veinous drainage) Pain sensitive Has own blood supply -- Middle meningeal artery Arachnoid Spongy/fibrous layer between the dura and pia Collagenous connective tissue Keep brain suspended in meninges Subarachnoid space Contains CSF Pia Mater Innermost layer Adheres almost indistinguishably to cortical surface, including sulci and gyri Difficult to see grossly or remove Dura Mater Dura Mater Middle meningeal artery Arachnoid Arachnoid Pia and arachnoid together are sometimes referred to as the leptomeninges CSF flows between the arachnoid and pia in the subarachnoid space Dural Reflections Dural Reflections Also called dural septa In certain places, the dura doubles on itself and forms a division or partition between parts of the brain Falx cerebri Tentorium cerebelli Falx Cerebri Extends down the longitudinal fissure, between the cerebral hemispheres Forms the triangular-shaped superior sagittal sinus superiorly Falx Cerebri Falx Cerebri Tentorium Cerebelli Extends inward between the cerebellum and occipital lobes Forms a “soft top” for the posterior cranial fossa Brain stem passes through tentorial notch Forms the transverse sinus posteriorly Tentorium Cerebelli Tentorium Cerebelli Tentorium Cerebelli Pathology of the Meninges Meningitis Infection/inflammation of the meninges Bacterial Viral Can progress to More widespread CNS infection Hydrocephalus, if flow of CSF is blocked (e.g., purulent accumulation) Bleeds Epidural Hematoma Rupture of middle meningeal artery Blood accumulates between dura and skull Mass effect compresses brain Fed by arterial perfusion…can grow quickly Bleeds Epidural Hematoma Mass effect Midline shift 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 brain Older people particularly susceptible. Why? Bleeds Subdural Hematoma -- crescent shaped Bleeds Subdural Hematoma Bleeds Subarachnoid Hemorrhage Rupture of cerebral vein or artery Bleeding into the subarachnoid space Blood hugs the surface of the brain (i.e., within the subarachnoid space). No mass effect Can block flow of CSF and result in hydrocephalus Bleeds Subarachnoid Hemorrhage Herniation Syndromes subfalcine cingulate herniation Cingulate gyrus herniates below falx cerebri Herniation Syndromes Uncal/Transtentorial Herniation Uncus (medial temporal lobe) herniates medially over the edge of the tentorium cerebelli into the brain stem Herniation Syndromes Tonsilar Herniation Cerebellar tonsil herniates through the foramen magnum Coming up next… Organization Developmental/Evolutionary Morphology 3-D Orientation to Internal Structures