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Brain Tidbit I: Nourishment to the brain. Meninges Ventricles Cerebro-Spinal Fluid. What are meninges? (review from spinal cord). Connective tissues around spinal cord For protection For nutrition (CSF) Three layers Pia mater Arachnoid mater Dura mater . 2 dural layers Endosteal
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Brain Tidbit I: Nourishment to the brain Meninges Ventricles Cerebro-Spinal Fluid
What are meninges?(review from spinal cord) • Connective tissues around spinal cord • For protection • For nutrition (CSF) • Three layers • Pia mater • Arachnoid mater • Dura mater
2 dural layers Endosteal Meningeal Form sinuses for blood drainage Arachnoid, pia mater same as spinal cord Meninges of the Brain
Falx cerebri Falx cerebelli Tentorium cerebelli Structures of the dura mater in skull
Blood supply to brain • Carotid, vertebral aa. • Drain to sinuses formed by dura mater • Blood-brain barrier • Capillary epithelial lining (endothelium) impermeable to water-soluble compounds • Only lipid solubles pass: CO2, O2, sugars, ammonia, small alcohols, lipids like prostaglandins, steroids
2 lateral ventricles in cerebral hemispheres Third ventricle in diencephaln Fourth ventricle in pons/cerebellum/ medulla oblongata Ventricles (the spaces in your brain…or the USS Enterprise)
Produced by choroid plexus of ventricles Passes to sub-arachnoid space of meninges through roof of fourth ventricle Flows down and around spinal cord Diffuses freely into nervous tissue Absorbed out of sub-arachnoid space and into blood at arachnoid villi/granulations in sagittal sinus 500 ml/day, turn-over in 8 hrs No feedback to choroid plexus—hydrocephalus is consequence of flow or absorption block Circulation of Cerebrospinal Fluid