Meninges and CF

Question 1

Protection of the brain & Spinal cord

Answer 1

• Cranium- skull; vertebral column - Bony protection
• Meninges
• Cerebrospinal fluid
• Blood-brain barrier- some drugs allowed in

Question 2

Cranial meninges

Answer 2

1. Dura Mater- composed of 2 layers periosteal, meningeal
2. Arachnoid Mater - ‘spider’ web like.
3. Pia Mater

Question 3

Meninges functions

Answer 3

1. Covers and protects CNS
2. Protects blood vessels & encloses venous sinuses
3. Contains CSF (encloses)
4. Forms partition within the skull

Question 4

What is Dura Matter

Answer 4

-Fibrous connective tissue attached to periosteum.
- composed of 2 layers
A) periosteal: outer layer attaches to bone
B) Meningeal: inner layer, closer to brain
*Two layers fused, except to enclose the dural sinuses – contains venous blood returning from the brain to jugular veins

Question 5

what is Arachnoid mater

Answer 5

thin membrane which covers the brain, not continuous with sulci, CSF circulates in subarachnoid space

• Arachnoid villi – projections protrude into Dural sinuses
• Transport SCF subarachnoid space to Dural sinuses

Question 6

what is Pia Mater

Answer 6

final layer in meninges, covers central nervous system, continuous with sulci
-delicate, follows convolutions.
tightly covers the brain & spinal cord & carries blood vessels – provide nourishment to nervous tissues

Question 7

what is Falx cerebri

Answer 7

extension of dura mater in the longitudinal fissure

Question 8

Meningitis

Answer 8

inflammation of meninges

Question 9

Ventricles & Cerebrospinal Fluid

Answer 9

4 cavities – ventricles filled CSF:

• Ventricle 1 & 2 – lateral ventricles occupies both hemispheres
• 3rd ventricle connected by a passage to each ventricles
• 4th ventricle connects via cerebral aqueduct to central canal of spinal cord

•Additional openings allow CSF to flow into subarachnoid space

Question 10

Hydrocephalus…..

Answer 10

Normally CSF is produced and drained.
-due to tumor, the drainage can be blocked. Accumulation of CSF in the head, exerts pressure on the brain. In infants, skull bones are not fused, hence the head enlarges, In adults, causes increased pressure on brain hence damaging the blood vessels and soft tissues. Treated by inserting a shunt, which drains the excess into abdominal cavity.

Question 11

Cerebrospinal fluid function

Answer 11

-Provides a stable chemical concentration
-Cushions & insulates delicate nervous tissue
-Buoyancy, absorb physical shocks to the brain
-Distribute nutritive materials to & removes wastes from nervous tissue
•Network of capillaries- choroid plexus project into each ventricle
•Ependymal cells surround these capillaries – provide blood – CSF barrier & controlling composition of CSF
•Blood is filtered as it passes through the ventricles forms CSF
•Lots of micro-vili to increase the amount of CSF made

Question 12

Where is CSF circulating

Answer 12

• Lateral ventricles 3rd and 4th ventricles
• Most pass into subarachnoid space and to central canal of spinal cord
• returns to the blood through arachnoid vili located in dural sinuses of the meninges

Question 13

how much CSF do we have

Answer 13

• Approximately 150ml of CSF at a time. Body keeps refreshing it because if there are any bacteria there then it needs to be gotten rid of, so there is no infection. Also gets rid of waste products
• contains: glucose, proteins, lactic acid, urea, cations, anions, WBC

Question 14

Blood Brain Barrier functions

Answer 14

• Protects the brain from “foreign substances” in the blood that may injure the brain.
• Protects the brain from hormones and neurotransmitters in the rest of the body. Don’t want neurotransmitters to leave the brain
• Maintains a constant environment for the brain.