T1 L12 Ventricular system & circulation of CSF

Question 1

What is the ventricular system?

Answer 1

Series of CSF-filled interconnected spaces

Continuous with subarachnoid space & central canal

Question 2

What forms the neural tube?

Answer 2

Neuroectoderm

Question 3

What forms the ventricles & central canal?

Answer 3

Lumen of the neural tube

Question 4

What does the ependymal layer line?

Answer 4

The ventricles & central canal

Question 5

What does the telencephalon form?

Answer 5

Cerebral hemispheres

Question 6

What does the diencephalon form?

Answer 6

Thalamus / hypothalamus

Question 7

What does the mesencephalon form?

Answer 7

Midbrain

Question 8

What does the metencephalon form?

Answer 8

Pons / cerebellum

Question 9

What does the myelencephalon form?

Answer 9

Medulla

Question 10

Where does the anterior horn sit?

Answer 10

In the frontal lobe

Question 11

What does the inferior horn sit?

Answer 11

Temporal lobe

Question 12

Where does the posterior horn sit?

Answer 12

Occipital lobe

Question 13

What separates the lateral ventricles?

Answer 13

Septum pellucidum

Question 14

Where does the corpus callosum sit?

Answer 14

In the roof of the lateral ventricles

Question 15

What are the lateral ventricle borders?

Answer 15

Caudate nucleus sits in lateral wall

Hippocampus sits in floor of inferior horn

Question 16

What is the function of the interventricular foramen?

Answer 16

Way for the lateral ventricles to communicate with the third ventricle
Also called Foramen of Monro

Question 17

What forms the roof of the third ventricle?

Answer 17

The fornix

Question 18

Where is the third ventricle?

Answer 18

Sits like cleft between thalami

Question 19

What is the cerebral aqueduct?

Answer 19

Way for the third ventricles to communicate with the fourth ventricle
Also called aqueduct of Sylvius

Question 20

What surrounds the cerebral aqueduct?

Answer 20

Surrounded by the midbrain

Question 21

What is the fourth ventricle surrounded by?

Answer 21

Hindbrain
Posterior - cerebellum
Anterior - pons & medulla
Lateral - cerebellar peduncles

Question 22

Describe the fourth ventricle communication

Answer 22

3 foramen exit into subarachnoid space:
2 foramen of Luschka (lateral)
1 foramen of Magendie (middle)
Into cisterns magna

Question 23

What is the function of the choroid plexus?

Answer 23

Produces CSF
Filters blood from branches of internal carotid & basilar arteries
Present throughout ventricles

Question 24

What is the structure of the choroid plexus?

Answer 24

Very simple

Capillary network surrounded by cuboidal epithelium

Question 25

What happens during CSF production?

Answer 25

1) Blood filtered through fenestrated capillaries | 2) Components transported through cuboidal epithelium into ventricles

Question 26

What are the functions of the tight junctions between the epithelial cells in the choroid plexus?

Answer 26

Prevent macromolecules from entering CSF Permeable to water & CO2 Forms blood-CSF barrier

Question 27

Describe cuboidal epithelium

Answer 27

Specialised ependyma Villi present to increase surface area Active transport of CSF components Bidirectional - uptake of metabolites into circulatory system

Question 28

What is the composition of CSF?

Answer 28

Differs in ionic composition compared to plasma Protein is much lower at 0.18 Differences due to regulation by active transport Very few cells Ideal for physiological functioning of neurons

Question 29

Describe the flow of CSF

Answer 29

Lateral ventricles --> inter ventricular foramen --> third ventricle --> cerebral aqueduct --> forth ventricle --> Luschka & Magendie foramina --> cisterns magna --> out ventricles into subarachnoid space

Question 30

Where is the subarachnoid space?

Answer 30

Between the Pia & arachnoid | Follows contours of brain

Question 31

What is the functional importance of the subarachnoid space?

Answer 31

CSF in contact with brain parenchyma to allow transfer of micronutrients into the brain & removal of metabolites

Question 32

What are arachnoid granulations?

Answer 32

Herniations of arachnoid membrane through dura mater into venous sinuses Mainly within superior sagittal & transverse sinuses

Question 33

Describe the absorption of CSF

Answer 33

CSF pressure must exceed that in venous sinuses (150mm in subarachnoid, 80mm water in venous sinuses) If venous pressure exceeds CSF pressure the tips of villi close off to prevent reflux of blood into subarachnoid space

Question 34

What is the volume of CSF?

Answer 34

500ml produced per day 90-140ml in system Continuously moving Excess absorbed by arachnoid granulations

Question 35

What are the main functions of CSF?

Answer 35

Hydraulic buffer to cushion brain against trauma Vehicle for removal of metabolites from CNS Stable ionic environment for neuronal function Transport of neurotransmitters & chemicals

Question 36

What can make CSF yellow?

Answer 36

(Xanthocromia) | Subarachnoid haemorrhage - lysis of RBC, haemoglobin release

Question 37

What can make CSF cloudy?

Answer 37

Multiple sclerosis - protein content increase | Bacterial meningitis - leucocytes are increased

Question 38

How do you sample CSF?

Answer 38

Lumbar puncture At lumbar cistern as there is no spinal cord here L3/L4 in adults L4/L5 in children

Question 39

What is hydrocephalus?

Answer 39

Dilation of brain ventricles Increased intracranial pressure Congenital or acquired

Question 40

What can cause hydrocephalus?

Answer 40

Blocked CSF circulation Impaired absorption Over secretion

Question 41

What are the symptoms of hydrocephalus?

Answer 41

``` Causes pressure on surrounding tissues which affects neurological function Headaches Vomiting Visual disturbance Papilledema Seizures Altered cognition Balance & coordination problems ```

Question 42

What is non-communicating hydrocephalus?

Answer 42

Blockage within ventricular system | CSF doesn't circulate over surface of brain

Question 43

What can cause a blockage in the ventricular system?

Answer 43

Tumour Cyst Stenosis

Question 44

What surgery is done for non-communicating hydrocephalus?

Answer 44

Insert shunt to reduce intracranial pressure

Question 45

What is Dandy-Walker syndrome?

Answer 45

Congenital malformation of cerebellum Obstruction within foramina of fourth ventricle - symmetrical dilation of lateral, third & fourth ventricles In infancy the child's head may become enlarged

Question 46

What is communicating hydrocephalus?

Answer 46

Obstruction in arachnoid villi | Movement of CSF into venous sinuses is impeded

Question 47

What are some causes of communicating hydrocephalus?

Answer 47

Impaired absorption following subarachnoid haemorrhage Trauma Bacterial meningitis