The meninges system

Reading instructions
To get the most out of this learning tool, please read:
Bear, Mark F, Connors, Barry W., Paradiso, Michael A. Neuroscience : exploring the brain. - 2 ed.
Chapter 7 page 163-252

Illustrations and anmimation

Three meninges cover the brain, the dura/dura mater, the arachnoid/arachnoidea and the pia/pia mater. The dura is the most superficial of the meninges and is separated from the arachnoid by a latent space, the subdural space. Between the arachnoid and the pia, the subarachnoidal space is located containing cerebrospinal fluid and cerebral arteries. The pia goes along with the vessels over the brains gyri and sulci.

The dura/dura mater
The dura is a fibrous tissue consisting of two layers, an outer periosteal layer and an inner meningeal layer. The dural layers are separated where the dural sinuses are placed. One of the dural septa, the falx cerebri/falx cerebri, extends between the two cerebral hemispheres whereas another dural septa, the tentorium cerebelli/tentorium cerebelli separates the cerebellum from the occipital lobes.and this dural septa is fused to the falx cerebri in the midline. In the anterior margin there is an opening, the tentorial notch/incisura tentorii where the superior brainstem, aquduct and vessels pass. There is also a dural septa between the two cerebellar hemispheres, the falx cerebelli. The diaphragma sellae forms an incomplete cover over the hypophysis allowing the pituatory stalk/infundibulum.

The dura mater in the anterior and the middle cranial fossae is sensory innervated by the trigeminal nerve while the dura in the posterior fossa is supplied by the upper three cervical nerves and by branches from the vagal/nervus vagus (X) and hypoglossal /nervus hypoglossus (XII) cranial nerves.

The arachnoid/arachnoidea
The arachnoid covers the subarachnoidal space wich is filled with cerebro spinal fluid (CSF). It does not go into sulci or fissures except to go along with the falx and the tentorium. Arachnoid granulations/granulationes arachnoidales are built up by microscopic villi that appear as berry-like aggregations protruding into the superior sagittal sinus and adjacent venous lacunae and in other sinuses and large veins. The arachnoid granulations are the locations of the absorbtion of CSF. The subarachnoidal space form widened spaces called cisterns and the cisterna magna is the biggest lying between the medulla and the cerebellum and is continuous with the spinal subarachnoidal space.

Pia/pia mater
The pia is a very delicate membrane that covers the surface of the brain and extends into fissures and over sulci.