Meninges, Ventricles, CSF Human Neurobiology ANHB 2217 Avinash Bharadwaj Semester 1, 2006 Week 2

Meninges Protective coverings for brain & spinal cord

Meninges Dura mater Cranial Spinal Arachnoid mater Pia mater

General Features Pia mater – soft, thin, delicate Arachnoid – delicate network Dura – tough, fibrous

Other Names! Dura – Pachymeninx – ‘tough’ Arachnoid (like a spider’s web) + Pia – leptomeninges

Cranial Dura Mater Bone Endosteal Sinus Meningeal

Folds of Dura Falx – the sickle Occupies the longitudinal fissure between cerebral hemispheres Tentorium – the tent Covers the cerebellum The opening accommodates the brainstem

Dural Venous Sinuses Veins with dural walls Separation of layers

Spinal Dura Not adherent to bone except… Epidural and subdural spaces

Ventricles Ependyma Pia The “hollow” brain Diagrammatic Cross Section

Pia and Ependyma In some locations pia mater and ependyma come together. A plexus of blood vessels “invaginates” the thin layer. Cerebrospinal fluid enters the ventricle across this membrane.

Ventricular System Lateral (1 + 2) 3 4 3rd 4th

Cerebrospinal Fluid Choroid plexus Ventricles Openings in the fourth ventricle Subarachnoid Space

CSF – Back to Blood Arachnoid Granulations (and villi)

Granulations Delicate projections into a sinus One-way flow into the sinus Increased pressure in the sinus blocks the flow Last slide!