Meninges

Question 1

What are the 3 protective layers surrounding the brain?

Answer 1

Dura mater - tough outer layer, anchored to the cranial bones

Arachnoid mater - attached to the inside of the dura mater. Arachnoid villi are protrusions through dura mater into the venous sinuses that allow CSF to exit subarachnoid space and enter the bloodstream

Pia mater - inner layer intimately covers folds and fissures of the brain

Question 2

What is the subarachnoid space?

Answer 2

Space between the arachnoid mater and the pia mater

spanned by connective tissue trabeculae

Contains CSF

Question 3

What are the 3 major dural septa?

Answer 3

Falx cerebri:

• sagittal
• separates cerebral hemispheres
• from crista galli anteriorly to tentorium cerebelli and IOP posteriorly

Falx cerebelli:

• sagittal
• separates cerebellar hemispheres
• anchors to tentorium cerebelli anteriorly and vertical crest of occiput posteriorly

Tentorium cerebelli

• transverse
• separates cerebrum (occipital lobes) from cerebellum
• anchors to occiput posteriorly and has a free border anteriorly