Meninges And Cisterns

Meninges

The arachnoid does not follow the contours of the brain as the pia mater does. But stretches across any irregularities on the brain. This leads to the formation of pools of subarachnoid space, especially around the brain stem. These extensions are called sub arachnoid cisterns.

The largest of them is called cerebellomedullary cistern(cisterna magna). This is used to tap the CSF. and this process is called the cisternal puncture. Others cisterns are the interpeduncular cistern, pontine cistern, supracallosalcistern, cisterna ambience etc.

Pontine cistern

P

C M

Cisterna magna

Cisterna ambiens

Dural folds The cranial dura has two layers(endosteal and meningeal) The meningeal layer forms two sickle shaped folds called falx cerebri and falx cerebelli and two tents; Tentorium cerebelli and diaphragma sellae.

Falx cerebri Tentorium cerebelli

Falx(L. sickle)

Between the two layers of Dura There are venous spaces called the Dural venous sinuses.

Tentorium cerebelli  Separates

the occipital lobes from the cerebellum.  Along its attached margins are the transverse sinuses.

To show the tentorial notch and free margins of tentorium

Falx cerebelli  Present

between the two cerebellar hemispheres.

Daiphragma sellae  Covers

the pituitary gland in the sella turcica. Pierced by the infundibulum (pituitary stalk).

Showing calcification of Falx cerebri