The Circle of Willis

Question 1

What arteries forms the circle of willis?

Answer 1

1. Anterior communicating
2. Anterior cerebral
3. Internal carotid
4. Ophthalmic a (comes off ICA)
5. Middle cerebral a
6. Posterior communicating a
7. Posterior cerebral a
8. basilar artery

Question 2

What two arteries from the basilar arteries and which part of the brainstem is it most closely related to?

Answer 2

Two vertebral a. and is related to pons

Question 3

What three branches come off the basilar artery?

Answer 3

1. Superior cerebellar a
2. Labyrinthine a (middle branch)
3. Anterior inferior cerebellar a

Question 4

Branches of which Arteries fuse to form the Anterior Spinal Artery?

Answer 4

Spinal artery

Question 5

What branch comes off each vertebral arteries?

Answer 5

Posterior inferior cerebellar a

Question 6

From which arteries do the L and R vertebral arteries arise?

Answer 6

Subclavian a.

Question 7

At what vertebral level do the L and R internal carotid arteries arise?

Answer 7

C4

Question 8

In which fissures does the anterior cerebral artery travel through?

Answer 8

Longitudinal fissure

Question 9

In which fissure does the middle cerebral artery travel through?

Answer 9

Lateral sulcus (sylvan fissure)

Question 10

In which fissure does the posterior cerebral artery through?

Answer 10

Calcarine fissure

Question 11

Which cerebral arteries supply the primary motor cortex?

Answer 11

Anterior and middle a

Question 12

Which cerebral arteries supply the primary sensory cortex?

Answer 12

Anterior and middle a

Question 13

Which cerebral arteries supply the primary visual cortex?

Answer 13

Posterior a

Question 14

Which cerebral arteries supply the primary auditory area?

Answer 14

Middle cerebral a

Question 15

Which cerebral arteries supply the area for olfaction?

Answer 15

Posterior a

Question 16

Which parts of the brain does the vertebro-basilar system supply?

Answer 16

Brainstem, occipital lobes, and cerebellum

Question 17

What area does the Anterior Cerebral Artery supply?

Answer 17

The Median Surface of the Cerebrum, and the superior part of the Superficial Surface of the Cerebrum

Question 18

What area does the Middle Cerebral Artery supply?

Answer 18

The Anterior Superficial Surface of the Cerebrum, except for the superior part

Question 19

What area does the Posterior Cerebral Artery supply?

Answer 19

The Posterior Superficial Surface of the Cerebrum (The Occipital Lobe, Midbrain, Hypothalamus, and the Pituitary)

Question 20

Which cerebral artery run immediately superior to the vertebrobasilar system?

Answer 20

Posterior cerebral artery

Question 21

Aneurysms of the posterior cerebral artery are common here and often result in palsy of CN III emerging just below.

What are the clinical manifestations of palsy of this cranial nerve?

Answer 21

Ptosis (LPS not innervated), abducted eye, depressed eye and diplopia

Question 22

Which cranial nerve emerges just above the superior cerebellar artery

Answer 22

Occulomotor nerve (CN III)

Question 23

Where can the carotid sinus be found?

Answer 23

This is a dilation located on the terminal part of the common carotid artery.

Question 24

What is the carotid sinus?

Answer 24

It is a pressure receptor which monitors flow of blow to the head, including the brain.

Sensory nerves from carotid sinus run in the glossopharyngeal nerve and vagus nerve.

Question 25

Where is the carotid body found?

Answer 25

In an area of the posterior wall of the terminal part of the common carotid artery in the neck.

Question 26

What is the function of the courted body?

Answer 26

It contain chemoreceptors which are sensitive to low levels of oxygen (anoxia). Sensory nerve from these receptors run in the glossopharyngeal nerves.

Question 27

What will be stimulated on the detection of Anoxia (Low Oxygen Levels) detected by the carotid body?

Answer 27

Increased heart rate, respiration rate and blood pressure.

Question 28

What are the Sympathetic Motor Nerves? And where can they be found?

Answer 28

From superior cervical ganglion form a plexus around the internal carotid artery. This plexus (C2-4) enters the skull, with the artery, through the carotid canal and continues along the main branches of the interior carotid artery.