MeningesMeninges

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.

Cisterna magna

Pontine cistern

P C

M

Cisterna ambiens

Dural foldsDural 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 cerebelliFalx(L. sickle)

Between the two layers of Dura There are venous spaces

called the Dural venous sinuses.

Tentorium cerebelliTentorium cerebelli

Separates the Separates the occipital lobes from occipital lobes from the cerebellum.the cerebellum.

Along its attached Along its attached margins are the margins are the transverse sinuses.transverse sinuses.

To show the tentorial notch and free margins of tentorium

Falx cerebelliFalx cerebelli

Present between the Present between the two cerebellar two cerebellar hemispheres.hemispheres.

Daiphragma sellaeDaiphragma sellae

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

                   

                    

Showing calcification ofFalx cerebri