The Dura Mater

In several places the meningeal dura mater extends inward to form flat septa that anchor the brain to the skill

The Dura Mater

The falx cerebri dips into the longitudinal fissue

It attaches to the crista galli of the ethmoid bone

The Dura Mater

The falx cerebelli forms a midline partition that runs along the vermis of the cerebellum

The Dura Mater

The tentorium cerebelli extends into the transverse fissue between the cerebral hemispheres and the cerebellum

The Arachnoid Mater

The middle membrane forms a loose brain covering over the surface of the cerebrum

It is separated from the dura mater by a narrow serous cavity, the subdural space

Beneath the arachnoid membrane is the wide subarachnoid space

The Arachnoid Mater

The subarachnoid space is filled with cerebrospinal fluid and contains the largest blood vessels serving the brain

Since the arachnoid is fine and elastic, these blood vessels are rather poorly protected

The Arachnoid Mater

Arachnoid villi protrude through the overlying dura mater and into the dural sinuses overlying the superior aspect of the brain

Cerebrospinal fluid is absorbed into the venous blood sinuses through these valvelike villi

The Pia Mater

The pia mater is a delicate connective tissue that is richly invested with tiny blood vessels

It is the only membrane that clings tightly to the brain, following its every convolution

Cerebrospinal Fluid (CSF)

CSF is found in and around the brain and spinal cord

It forms a liquid cushion that gives bouyancy to the CNS organs

By floating the brain, the CPF reduces brain weight by 97% and thus prevents the brain from crushing under its own weight

CSF also protects the brain and spinal cord from trauma

CSF also helps to nourish the brain

Cerebrospinal Fluid (CSF)

CSF is a similar in composition to blood plasma, from which it arises

It contains less protein and more vitamin C and its ion concentration is different

CSF composition is important in the control of cerebral blood flow