Lecture 2 (10/2)/ week 1.2

Question 1

List and describe the 3 spaces created by the meninges. Where are they located? What is contained within them?

Answer 1

1) Epidural space: between skull and dura; the middle meningeal artery runs through here
2) Subdural space: between dura and arachnoid; bridging veins traverse this space
3) Subarachnoid space: between arachnoid and pia; contains CSF and several major arteries that send branches inward through the pia

Question 2

Does the spinal cord have meninges, or does it stop at the brain?

Answer 2

Meninges continue down spinal cord, with the addition of an epidural fat layer.

Question 3

1) Define ventricles
2) What does the choroid plexus do? Where is it?

Answer 3

1) Cavities in the brain that contain CSF
2) Produces CSF; inside the ventricles

Question 4

Flow of CSF (6 steps)

Answer 4

1) Flows from lateral ventricles
3) To third ventricle via foramen of Monro, from the third
3 )To the fourth ventricle through the Sylvian aqueduct
4) Out the foramina of Luschka and Magendie
5) To subarachnoid space and
6) Absorbed into venous bloodstream through arachnoid granulations

Question 5

Where are the 4 ventricles located?

Answer 5

1&2) Two lateral ventricles (one in each hemisphere)
3) Third ventricle in the diencephalon (thalamus, hypothalamus,)
4) Fourth is posterior and surrounded by the pons, medulla and cerebellum

Question 6

1) What is the normal volume of CSF in an adult?
2) What produces CSF, and how much is produced a day?

Answer 6

1) 150cc
2) The choroid plexi produce about 500 cc/day

Question 7

1) What are cisterns?
2) Where is the lumbar cistern and what does it house? Why is this cistern clinically significant?

Answer 7

1) Pools of CSF in the subarachnoid space
2) Located in lumbar spine houses cauda equina; the location CSF fluid is taken for lumbar puncture

Question 8

What level is the lumbar cistern below?

Answer 8

L1-L2

Question 9

Define the blood brain barrier

Answer 9

Capillary endothelial cells in the brain that are closely linked by tight junctions

Question 10

How do substances pass through the blood brain barrier and into the brain?

Answer 10

By active transport; don’t just freely flow in

Question 11

1) Why are there defined breaks in the blood-brain barrier?
2) What can disrupt the blood-brain barrier?
3) What does a disrupted blood-brain barrier cause?

Answer 11

1) To allow the brain to respond to chemical changes in the body (to release hormones, respond to toxins, etc.)
2) By trauma, tumors, infection, etc
3) Causes fluid to leak into the interstitial space, which causes swelling

Question 12

What two things add several layers of protection to the brain?

Answer 12

Cranial vault and meninges

Question 13

The skull has multiple openings for entry and exit called _________

Answer 13

Foramina.

Question 14

1) What is the largest foramina called?
2) What meets and exits through there?

Answer 14

1) The foramen magnum. 2) The spinal cord and medulla meet and exit here.

Question 15

1) What is the final layer of protection within the skull surrounding the brain?
2) What is the tentorium cerebelli?

Answer 15

1) The meninges
2) A tent like sheet of dura over the cerebellum.

Question 16

What are the 3 layers of the meninges? Briefly describe each

Answer 16

1) Dura mater: outermost meninge adheres to the skull. Tough and durable
2) Arachnoid mater: wispy, spidery layer
3) Pia mater: adheres closely to the brain surface

Question 17

What is the average amount of CSF in an adult?

Answer 17

150cc