02.1 Environment of the brain, bleeds and hydrocephalus

Question 1

What are the functions of cerebrospinal fluid?

Answer 1

Protection - Cushions the brain
Buoyoncy - reduces the net weight of the brain
Chemical stability - low potassium allows the brain to function

Question 2

Briefly describe the general circulation of cerebrospinal fluid.

Answer 2

Lateral ventricles (I + II)
Third Ventricle (made by the borders of the right and left thalamus)
Cerebral aqueduct
Fourth Ventricle
Central canal

Question 3

What drains the CSF?

Answer 3

Arachnoid granulations drain the CSF into the dural venous sinuses.

Question 4

What are the main blood vessels supplying the brain and what vessels are they derived from?

Answer 4

Anterior and Middle Cerebral arteries from the Internal Carotids
Basilar and Posterior Cerebral Arteries from the Vertebral arteries

Question 5

What does the anterior cerebral artery supply?

Answer 5

Medial portion of the cerebral hemispheres

Question 6

What does the middle cerebral artery supply?

Answer 6

Lateral portion of the cerebral hemispheres

Question 7

What does the posterior cerebral artery supply?

Answer 7

Posterior brain

Question 8

What does the basilar artery supply?

Answer 8

Cerebellum and brainstem

Question 9

How do the cerebral arteries join?

Answer 9

Circle of Willis. Anterior and posterior communicating arteries form a ring at the base of the brain.

Question 10

What are the meningeal layers?

Answer 10

Periosteal dura
Meningeal dura
Archnoid mater
Pia mater

Question 11

Which layer of the meninges forms the falx cerebri?

Answer 11

Meningeal dura

Question 12

Which meningeal layer prevents encephalitis?

Answer 12

Pia mater prevents bacteria entering the brain.

Question 13

What are the 3 main types of intracranial hemorrhage?

Answer 13

Extradural haematoma
Subdural haematoma
Subarachnoid haemorrhage

Question 14

What is the usual cause of an extradural haematoma?

Answer 14

Trauma. Pterion fracture and the middle meningeal artery being severed.

Question 15

What type of vessel is an extradural bleed from?

Answer 15

Artery

Question 16

What causes a subdural haematoma?

Answer 16

Bridging veins being damaged

Question 17

What layers does an extradural haematoma occur between?

Answer 17

Skull and periosteal dura

Question 18

What layers does a subdural haemorrhage occur between?

Answer 18

Dura mater and Arachnoid mater

Question 19

What type of vessel causes a subdural haemorrhage?

Answer 19

Veins

Question 20

What causes a subarachnoid haemorrhage?

Answer 20

Berry aneurysms bursting

Question 21

Who is at a greater risk of berry anuerysm formation?

Answer 21

Polycystic kidney disease

Question 22

What is hydrocephalus?

Answer 22

An abnormal collection of CSF in the ventricles leading to raised ICP

Question 23

What is communicating hydrocephalus?

Answer 23

No flow obstruction. Usually due to impairment of reabsorption by arachnoid granulations

Question 24

What is non-communicating hydrocephalus?

Answer 24

Flow obstruction. Usually of the cerebral aqueduct.

Question 25

How can hydrocephalus be treated?

Answer 25

Peritoneal shunt

Question 26

What forms the blood brain barrier?

Answer 26

Tight vascular endothelial junctions
Feet of astrocytes
Interneurones ‘plug the gaps’

Question 27

What can move across the blood brain barrier?

Answer 27

Water, O2, CO2 can freely move

Glucose and amino acids are transported