CNS and Meninges

Question 1

Describe the appearance of CSF

Answer 1

Clear, colourless mostly composed of water

Question 2

Where is CSF produced?

Answer 2

Secretory epithelium of the choroid plexus in the ventricles

Question 3

What is the volume of CSF circulating in the CNS at any one time?

Answer 3

150ml

Question 4

State three major function of CSF

Answer 4

• Mechanical protection (shock absorber of which the brain sits in)
• Homeostatic function (pH and transport of hormones)
• Circulation (exchange of nutrients/waste)

Question 5

How obtained for analysis?

Answer 5

Lumbar puncture

Question 6

How does the choroid fissure develop?

Answer 6

Arteries invaginate the roof of the ventricle to form the choroid tissue, this causes the ependymal cells and vessels to enlarge to villi and form the plexus

Question 7

What causes hydrocephalus?

Answer 7

CSF outflow obstruction which can cause enlargement of the ventricular space

Question 8

How are the ependymal cells held together?

Answer 8

Tight junctions

Question 9

What ions are involved in the production of CSF from blood?

Answer 9

Na+
Cl-
HCO3-

Question 10

How does fluid move across the membrane?

Answer 10

Active sodium transport, electrical gradient pull chloride and water moves by osmosis

Question 11

How is CSF different to blood?

Answer 11

Lower potassium, glucose and protein

Higher sodium and chlorine

Question 12

Is the production of CSF active or passive?

Answer 12

Active process does not depend on arterial BP

Question 13

How many ventricles are there?

Answer 13

Two lateral, a third and a fourth

Question 14

State the connections between the ventricles

Answer 14

Foramen of monroe - laterals to third
Aqueduct of sylvius - third to fourth
Foramen of magendie and foramen of luschka - fourth ventricle to subarachnoid space

Question 15

Where does the CSF go from the subarachnoid space?

Answer 15

Drains into the arachnoid villi of dural venous sinuses

Question 16

What does the blood brain barrier consist of?

Answer 16

Capillary endothelium, its basal membrane and perivascular astrocytes

Question 17

In the BBB what type of junction are between the endothelial cells?

Answer 17

Tight junctions - prevent paracellular movement

Question 18

Do all areas of the brain have a BBB?

Answer 18

No - circumventricular organs and the pineal gland do not

Question 19

Name three types of tumour related to CSF

Answer 19

• colloid cyst (often in interventricular foramen)
• ependymonas
• choroid plexus tumour

Question 20

What can ventricular haemorrhage result in?

Answer 20

• epidural haematoma
• subdural haematoma
• subarachnoid haematoma

Question 21

What are the symptoms of idiopathic intracranial hypertension?

Answer 21

Headache and visual disturbance

Question 22

What is papilloedema?

Answer 22

Optic disc swelling due to increased intracranial pressure as a result of excess CSF

Question 23

What are the symptoms of papilloedema?

Answer 23

Enlarged blind spot, blurring of vision and visual obscurations

Question 24

What is the serious complication of papilloedema?

Answer 24

Compression of optic nerve which can lead to loss of vision

Question 25

What conditions can increase intracranial pressure?

Answer 25

• tumours
• head injury
• hydrocephalus
• meningitis
• stroke

Question 26

What is the Monro Kellie Hypothesis?

Answer 26

Intracranial volume is constant and the cranial cavity is inelastic so there is no room for expansion

Question 27

What are the ocular symptoms for increased intracranial pressure?

Answer 27

Blurred vision 
Double vision 
Loss of vision 
Papilloedema 
Pupillary changes

Question 28

What is special with the optic nerve?

Answer 28

They are tracts of the CNS covered by meninges

Question 29

What happens to the optic nerve when ICP increases?

Answer 29

It gets compressed as well as the central artery and vein which leads to a bulging/swollen optic disc

Question 30

What is a swollen optic disc known as?

Answer 30

papilloedema

Question 31

If compression of the oculomotor nerve occurs what happens?

Answer 31

Only the superior oblique and lateral rectus still have innervation so the pupil will be turned down and out

Question 32

How will oculomotor nerve compression present?

Answer 32

Dilated pupil, ptosis, down and out look

Question 33

How can the oculomotor nerve be stretched or compressed?

Answer 33

The brain can herniate through folds created by the dura mater and if the medial temporal lobe herniates through the tectorial notch the oculomotor nerve can be affected

Question 34

Why is the trochlear nerve susceptible to damage?

Answer 34

It has a long intracranial course

Question 35

What is the effect of compression of the trochlear nerve?

Answer 35

Paralysis of the superior oblique which means the inferior oblique is unopposed

Question 36

How will trochlear nerve compression present?

Answer 36

Eye cannot move inferomedially - diplopia when looking down

Question 37

What will stretching of the abducent nerve cause?

Answer 37

Paralysis of the lateral rectus muscle

Question 38

How will stretching of the abducens present?

Answer 38

Medial deviation of the eye

Question 39

Name the five regions of the brain

Answer 39

Telencephalon - cerebral hemispheres 
Diencephalon - thalamus and hypothalamus 
Mesencephalon - midbrain 
Metencephalon - pons and cerebellum 
Myelencephalon - medulla

Question 40

Name four types of glial cell

Answer 40

Astrocyte
Oligodendrocyte
Microglia
Ependymal