Cerebral Vasculature

Question 1

What’s the function of the blood-brain barrier?

Answer 1

Separates brain tissue from blood circulation

1. Maintain constant intracerebral chemical environment
2. Control of entry of cells & molecules
3. Protect against osmotic change

Question 2

How does the blood-brain barrier do its job?

Answer 2

Tight junctions in blood vessel endothelium

Basement membrane

Astrocyte foot processes and pericytes

Question 3

What are astrocytes?

Answer 3

Star shaped glial cells in the brain and spinal cord

Question 4

What are pericytes?

Answer 4

Contractile cells that wrap around the endothelial cells of capillaries and venules of brain

Question 5

What is a glial cell?

Answer 5

Non-neuronal cells that maintain homeostasis, form myelin, and provide support and protection for neurons in the brain and peripheral nervous system.

Question 6

Name the 4 main arteries that supply the brain.

Answer 6

L&R vertebral arteries

L&R internal carotid arteries

Question 7

Where do the vertebral arteries arise from?

Answer 7

Subclavian arteries

Question 8

Describe the journey of vertebral arteries from Subclavian to brain.

Answer 8

Subclavian > ascend up posterior side of neck through holes in transverse processes of the cervical vertebrae (foramen transversarium) > cranial cavity via foramen magnum

Question 9

Name 3 branches of the vertebral arteries and name their destination.

Answer 9

Meningeal branch - falx cerebri

Ant and Post spinal arteries - entire length of spinal cord

Post Inf cerebellar artery - cerebellum

Question 10

What happens to the vertebral arteries after the branches have branched off?

Answer 10

Converge to form basilar artery

Question 11

What do branches of basilar artery supply?

Answer 11

Cerebellum and pons

Question 12

What does the basilar artery bifurcate into?

Answer 12

Post cerebral arteries

Question 13

Where do the internal carotids originate from?

Answer 13

Where the left and right common carotids bifurcate - at C4

Question 14

How do the internal carotids enter the skull?

Answer 14

Via carotid canal of temporal lobe

Question 15

Name 3 branches of the internal carotid arteries and what they each supply.

Answer 15

Ophthalmic artery - structures of orbit

Posterior communicating artery - anastomotic connecting vessel in COW

Anterior cerebral artery - cerebrum

Question 16

What happens to the internal carotid arteries after the branches have branched off?

Answer 16

They become the middle cerebral artery which supplies the lateral cerebrum

Question 17

Name the three main constituents of the COW and the two connecting vessels.

Answer 17

Main:
Ant cerebral arteries
Internal carotid arteries
Post cerebral arteries

Connecting:
Ant communicating
Post communicating

Question 18

Draw and label the COW.

Answer 18

:)

Question 19

Name the three cerebral arteries! And say what lobes of the cerebrum they supply

Answer 19

Anterior - medial part of frontal lobes, superior medial part of parietal lobes

Middle - lateral part of temporal, frontal, parietal

Posterior - occipital, inferior part of temporal

Question 20

What is an aneurysm?

Answer 20

A localised permanent dilation of a blood vessel

Question 21

What is a berry aneurysm?

Answer 21

An aneurysm that occurs at the bifurcation of branches of the Circle of Willis. Forms a sac/berry shape.
It’s when the muscular arterial wall is replaced with fibrosis.
Leads to a subarachnoid haemorrhage.

Question 22

Symptom of berry aneurysm?

Answer 22

Sudden thunderclap headache

Question 23

What is a TIA?

Answer 23

Transient Ischaemic Attack - mini stroke where symptoms clear up within 24 hours

Question 24

What is a CVA?

Answer 24

Cerebrovascular accident - stroke vascular lesion causing irreversible loss of central nervous tissue

Question 25

Types of Strokes? Explain them.

Answer 25

Ischaemic - Thrombus or atheromatous plaque that blocks a vessel starving a region of brain of oxygen

Haemorrhagic - Subarachnoid or intracranial bleed

Question 26

What % do Ischaemic strokes account for?

Answer 26

85%

Question 27

What % do Haemorrhagic strokes account for?

Answer 27

15%

Question 28

What else can cause a stroke?

Answer 28

Vertebral/carotid dissection (tearing of artery wall)

Space occupying lesion (cancer for eg)

Question 29

Describe venous blood flow from deep within the brain to the Superior Vena Cava.

Answer 29

Deep cerebral veins > Superficial cerebral veins > Venous sinuses > Internal jugular vein >
Subclavian vein > SVC

Question 30

What is the blood-CSF barrier?

Answer 30

Separates the CSF and blood

Question 31

Name the 3 parts of the blood-CSF barrier.

Answer 31

1. Choroidal epithelial cells - interconnected by tight junctions and secreting CSF
2. Basal membrane
3. Endothelium of pia mater capillaries

Question 32

Describe the layers of the blood-CSF barrier from blood > CSF.

Answer 32

Blood > Endothelium of pia mater capillaries > Basement membrane > choroid cells > CSF

Question 33

Give 2 features of the choroid cells.

Answer 33

Microvilli to increase surface area

Enzymes to allow active transport of ions and metabolites in and out

Question 34

Where is the blood-CSF barrier?

Answer 34

In the choroid plexus - which is found in lateral, 3rd and 4th ventricles

Question 35

What is the cavernous sinus?

Answer 35

A drainage pathway of the brain.

A large collection of thin walled veins creating a cavity

Question 36

Where does the cavernous sinus receive blood from?

Answer 36

Brain and tributaries of the face

Question 37

How many cavernous sinuses are there?

Answer 37

2 - one for each hemisphere of the brain

Question 38

Where is the cavernous sinus?

Answer 38

Base of brain

Bordered by temporal bone and sphenoid bone

Question 39

What is the mnemonic for remembering what nerves and vessels go through the cavernous sinus?

Answer 39

O TOM CAT

Oculomotor

Trochlear
Ophthalmic trigeminal
Maxillary trigeminal

Carotid (internal)
Abducens
Trochlear

Question 40

Draw the cavernous sinus.

Answer 40

:)