Blood supply, meninges and CSF

In what order are the three meninges on the brain (outside to inside)

Dura mater, arachnoid mater, pia mater

Describe the dura mater

Thick, fibrous. Two layer, inner = meningeal, outer = periosteal/endosteal. Innverbated by trigeminal (sensory). Vascular. Has two fissures (folds in which you can see the separate layers) the falx cerebri and tentorium cerebri.

Describe the arachnoid mater

Thin, transparent. Forms a web like structure, avascular, little innervation.

Describe the subdural space

Potential space with small amount of fluid, between dura and arachnoid.

Describe the subarachnoid space

Between arachnoid and pia mater. Contains CSF, blood vessels

Describe the pia mater

Thin, highly vascular, dense nerves, follows blood vessels into tissue sand merges with Adventist, closely adherent to tissues.

Describe the epidural space

Space between bone of vertebrae and vertebral canal, filled with fat and CT.

Properties of CSF

Cell free, protein free, low aa content, low+stable K+, low glucose.

Functions of CSF

Physical protection of CNS tissues, circulation of nutrients and neurotransmitters, stable environment, volume buffer to alLow for slight swelling.

Function and location of choroid plexi

Produces CSF, found in the third ventricle (surrounding ventricle)

How is CSF drained

Reabsorption into circulation by arachnoid villi stretching into the subarachnoid space from the venous sinuses of the dura mater.

Describe the arterial supply to the brain in dogs

Blood from internal carotid and basilar arteries feed the cerebral arterial circle. This gives raise to 5 main artery pairs. 3 pairs of cerebral arteries (rostral, middle, caudal). Two pairs of cerebella arteries (rostral and caudal)

Name and describe two locations where CSF can be drained

Atlanto-occipital junction, between atlas of the skull.

Cerebromedullary cistern, beyond end of spinal cord where the subarachnoid space widens.

What is the issue with few anastomoses between arteries and collateral vessels in the brain

CNS contains functional ems arteries, so if one is occluded or ruptured, the area of tissue supplied by that vessel will be compromised (ischemia/infarction)

Describe Venous drainage in the dog CNS

Blood slow, bidirectional, intermittent. Large venous sinuses within the dura mater, and dorsal / ventral sinuses in the cranium.