NB4 Bloodsupply of brain, role of CSF

Question 1

what is the basillar aa. fromed by?

Answer 1

vertebral aa

Question 2

What branches off the internal carotid aa?

Answer 2

opthalmic aa- heads forwards to eye

anterior choroidal aa comes off before posterior communicating aa. and heads in the same direction as post. communicatingaa. passes posteriorly to join posterior cerebral aa to internal carotid middle cerebral aa. pans laterally to supply temple region anterior cerebral aa. pass anteriorly it is connected via the anterior communicating aa.

Question 3

What joins the vertrbral arteries together? 2) what branches off the vertebral aa.

Answer 3

1) ant. spinal aa. 2) post. inf. cerebellar aa.

Question 4

What supplies the cerebellum?

Answer 4

Branches of vertebral aa. Post. inf. cerebellar aa. (post. and inf. surfaces Branches of basillar aa. anterior inferior cerebellar aa. (ant. and inf. surfaces) sup. cerebellar aa. (sup. surface of cerebellum)

Question 5

What can occur if basillar aa. is occluded:

Answer 5

locked in syndrome

Question 6

What are the branches coming off the basillar aa. go from post to ant:

Answer 6

anterior inferior cerebellar aa. superior cerebellar aa. pontine aa. posterior cerebral aa.

Question 7

Identify the anteior cerebral aa. middle cerebral aa anterior communicating aa internal carotide aa.

Answer 7

j

Question 8

Identify the following branches of the vertebral aa.:

ant. spinal aa.

post spinal aa.

post inf. cerebellar aa

Answer 8

Question 9

Identify the following branches of the basillar aa.:

ant. inf. cerebellar aa.

sup cerebellar aa.

post. cerebraL aa

PONTINE AA

Answer 9

Question 10

What are the main aa. of the cortex

Answer 10

posterior cerebral

middle cerebral

anterior cerebral

Question 11

1) function of the blood brain barrier:
2) What are the layers fo the blood brain barrier:

Answer 11

1) semipermeable membrane seperating the blood from cerebrospinal fluid

It controls the movement of cells, particles and large molecules

2) endothelial cells (joined together by tight junctions= diffusion barrier- stop entry of toxic substances)

astrocytic end-feet ensheath vessel wall ( maintain tight junction barrier, but no barrier function and pick up nutrients and deliver to nerve cells, subsequently prevent toxic substances from reaching the brain)

Question 12

Where is the cerebrospinal fluid made?

Answer 12

choroid pleus (70%)

ependymal cells (epithelia lining ventricles) (30%)

Question 13

Describe the route of cerebrospinal fluid:

Answer 13

1) lateral ventricles to third ventricles through intraventricular foramen ( foramen of munro)
2) passes through 3rd ventricle to 4th ventricle through cerebral aquaduct ( aquaduct of sylvius)
3) then into subarachnoid space via foramina of luschka or magendie
4) CSF will flow into blood through arachnoid villi which contain one-way valves, high to low pressure.

Question 14

Roles of CSF:

Answer 14

1. allows brain to “float”- reduce pressure on brainstem
2. Protective
3. removes waste metabolites
4. stable ionic env. for CNS
5. endocrine medium (allows drugs to move)

Question 15

Composition of CSF:

Answer 15

1. small amounts of protein
2. glucose
3. ions - calcium, potassium .,.,.

Question 16

Name

Answer 16

lateral ventricle

Question 17

Name

Answer 17

3rd ventricle

Question 18

Name

Answer 18

4th ventricle