Ventricular system

Question 1

Describe the ventricles associated with each part of the brain

Answer 1

Lateral ventricles surrounded by telencephalon–>cerebral hemispheres

Third ventricle surrounded by diencephalon forms the thalamus and hypo

Cerebral aqueduct - mesencephalon - - midbrain

fourth ventricle - metencephalon - medulla

Question 2

describe structure of lateral ventricles

Answer 2

anterior horn (frontal lobe)
body ( parietal lobe) 
posterior horn (occipital lobe) 
Inferior horn (temporal lobe)

Question 3

what separates the lateral ventricles?

Answer 3

septum pellucidum

Question 4

what are the borders of the lateral ventricles

Answer 4

Roof - corpus callosum
separated by septum pallucidum
caudate nucleus in lateral wall
hypocampus in floor of inferior horn

Question 5

what connects the lateral ventricles with the third ventricle?

Answer 5

interventricular foramen

Question 6

what connects 3rd to 4th ventricle

Answer 6

cerebral aqueduct

Question 7

describe 4th ventricle

Answer 7

cerebellum posterior
pons and medulla anterior
cerebellar peduncles lateral

Question 8

what connects from 4th ventricles

Answer 8

3 foramen exit into subarachnoid space
2 from foramen of lushka laterally
and one foramen of magendie - middle
into cisterna magna

Question 9

csf production

Answer 9

by choroid plexus

filters blood from branches of internal carotid and basilar arteries

Question 10

structure of choroid plexus

Answer 10

capillary network - fenestrated capillaries
surrounded by cuboidal epithelium
When blood is filtered through the fen cap the components are transported through cub epithelium into ventricles

Tight junctions between epithelial cells to prevent macromolecules from entering CSF and is permeable to water and co2 - forms the blood csf barrier

Question 11

why is it important for the csf to be in contact with the brain parencyhma?

Answer 11

to transfer micronutrients into the brain

and to remove metabolites

Question 12

absorption of csf

Answer 12

csf pressure must exceed venous pressure if VP exceeds csf pressure the tips of villi will close off and prevent reflux of blood into sub A space
arachnoid villi act as one way valves

Question 13

csf volume

Answer 13

500 ml produced daily

140 ml in system - 30 ml in ventricles and 110ml in subA space

Question 14

functions of CSF

Answer 14

1. Hydraulic buffer to cushion brain against trauma
2. Vehicle for removal of metabolites from CNS
3. Stable ionic environment for neuronal function
   (communicates with brain interstitial fluid via pia)
4. Transport of neurotransmitters and chemicals

Question 15

what does yellow CSF indicate?

Answer 15

subA haemorrhage

Question 16

cloudy csf

Answer 16

MS - protein content

Bacterial meningitis - leucocytes

Question 17

at what level do you take lumbar puncture?

Answer 17

L3/4 adults
L4/5 children

at the lumbar cistern

Question 18

what is hydrocephalus?

Answer 18

Dilation of brain ventricles

Due to blocked CSF circulation, impaired absorption, or over secretion
causes increased intracranial pressure
pressure on surrounding tissues affects neuro function
Symptoms include: headaches, vomiting, visual disturbances, papilledema (swelling of optic disc), seizures, altered cognition, balance and coordination problems

Question 19

describe non-communicating hydrocephalus

Answer 19

blockage within the ventricular system due to tumour, cyst, stenosis causing narrowing of cerebral aqueduct
csf does not circulate over brain surface
surgery - shunt

Question 20

dandy walker syndrome

Answer 20

Congenital malformation of the cerebellum (1:30,000 births)

Obstruction within foramina of fourth ventricle:
- Symmetrical dilation of lateral, third and fourth ventricles

Question 21

communicating hydrocephalus

Answer 21

Obstruction in the arachnoid villi

Movement of CSF into venous sinuses is impeded

• E.g. Impaired absorption following subarachnoid haemorrhage, trauma or bacterial meningitis