Blood Supply of the Cerebrum

Question 1

What are the four main arteries that supply the brain?

Answer 1

Two internal carotid arteries
Two vertebral arteries

Question 2

Where do the 4 main arteries of the brain anastomose to form the Circle of Willis?

Answer 2

On the inferior surface of the brain.

Question 3

Through which structure do the internal carotid arteries enter the cranial cavity?

Answer 3

Through the carotid canal.

Question 4

What are the terminal branches of the internal carotid artery?

Answer 4

Anterior cerebral artery (ACA)
Middle cerebral artery (MCA)

Question 5

What are the main relations of the internal carotid artery?

Answer 5

Cavernous sinus: The artery runs anteriorly within it.
Optic chiasma: The artery turns upwards lateral to the chiasma.

Question 6

Where does the internal carotid artery run after entering the cranial cavity?

Answer 6

It runs anteriorly forwards within the cavernous sinus.

Question 7

What landmark does the internal carotid artery turn upwards near?

Answer 7

It turns upwards lateral to the optic chiasma.

Question 8

Where does the internal carotid artery terminate?

Answer 8

By dividing into the anterior cerebral artery and middle cerebral artery.

Question 9

What is the Circle of Willis?

Answer 9

A circular anastomosis of arteries at the base of the brain, allowing collateral blood flow in case of arterial obstruction.

Question 10

Which arteries contribute to the Circle of Willis?

Answer 10

Anterior circulation: Internal carotid arteries, anterior cerebral arteries, anterior communicating artery.

Posterior circulation: Posterior cerebral arteries, posterior communicating arteries.

Question 11

Through which structures do the vertebral arteries ascend in the neck?

Answer 11

Through the foramina in the transverse processes of the upper six cervical vertebrae.

Question 12

How do the vertebral arteries enter the cranial cavity?

Answer 12

Through the foramen magnum.

Question 13

What do the vertebral arteries form after joining together?

Answer 13

The basilar artery.

Question 14

Name the 7 arteries that form the Circle of Willis.

Question 15

What percentage of people have the classic anatomical configuration of the Circle of Willis?

Answer 15

Roughly 35%

Question 16

What is the primary function of the Circle of Willis?

Answer 16

To allow collateral circulation of blood if one part of the circle becomes blocked or narrowed.

Question 17

What condition does the Circle of Willis help prevent?

Answer 17

Ischemia by ensuring blood supply to affected areas via collateral flow.

Question 18

Clinical: How is blood rerouted if the left internal carotid artery is severely blocked?

Answer 18

Blood flows via the contralateral anterior and posterior communicating arteries to supply the left middle and anterior cerebral arteries.

Question 19

Where is the Circle of Willis located in relation to the brainstem?

Answer 19

It is located on the ventral surface of the pons.

Question 20

What is a practical example of collateral circulation in action?

Answer 20

In cases of severe blockage of one artery (e.g., left internal carotid), the Circle of Willis allows blood to bypass the blockage and maintain perfusion via the communicating branches.

Question 21

Which cerebral artery is located close to the corpus callosum and supplies the medial surface of the brain?

Answer 21

The anterior cerebral artery (ACA).

Question 22

What part of the brain does the anterior cerebral artery primarily supply?

Answer 22

A large part of the medial surface of the cerebral hemisphere.

Question 23

Which cerebral artery lies in the lateral sulcus?

Answer 23

The middle cerebral artery (MCA).

Question 24

What part of the brain does the middle cerebral artery primarily supply?

Answer 24

A large part of the lateral surface of the cerebral hemisphere.

Question 25

Why are these vascular territories clinically significant?

Answer 25

They correspond to specific functional areas, so a blockage in these arteries can cause distinct patterns of neurological deficits depending on the affected region.

Question 26

Which arteries supply the midbrain?

Answer 26

Posterior cerebral artery Superior cerebellar artery Basilar artery

Question 27

Name the arteries that supply the pons.

Answer 27

Basilar artery Pontine arteries Anterior inferior cerebellar artery (AICA) Superior cerebellar artery

Question 28

Which arteries supply the medulla oblongata?

Answer 28

"BV And PP": Basilar artery Vertebral artery Anterior spinal artery Posterior spinal artery Posterior inferior cerebellar artery (PICA)

Question 29

Which arteries supply the cerebellum?

Answer 29

Superior cerebellar artery (SCA) Anterior inferior cerebellar artery (AICA) Posterior inferior cerebellar artery (PICA)

Question 30

What are the three longitudinal arteries supplying the spinal cord?

Answer 30

Two posterior spinal arteries One anterior spinal artery

Question 31

How is the spinal cord's blood supply reinforced?

Answer 31

By small segmental arteries that arise from arteries outside the vertebral column and enter through the intervertebral foramina

Question 32

What is the role of anastomoses on the spinal cord surface?

Answer 32

The arteries anastomose to supply branches into the white and gray matter of the spinal cord.

Question 33

What would be the effect of occlusion of the anterior spinal artery?

Answer 33

It could lead to anterior spinal cord syndrome, causing motor deficits and loss of pain/temperature sensation below the lesion.

Question 34

Which artery's occlusion is most commonly implicated in lateral medullary syndrome?

Answer 34

The posterior inferior cerebellar artery (PICA).

Question 35

Which areas of the primary motor cortex are most affected by a loss of blood supply from the ACA?

Answer 35

The areas responsible for the lower limb and perineum of the contralateral side.

Question 36

What functional deficit can result from the ACA affecting the pelvic floor muscles?

Answer 36

Incontinence due to loss of control over pelvic floor muscles.

Question 37

How does ACA blockage affect motor and sensory function?

Answer 37

Loss of sensation and motor function for the body, except for the lower limb and perineum.

Question 38

What speech-related areas does the ACA supply, and what happens if they are affected?

Answer 38

Broca’s motor speech area: Impacts the ability to speak. Wernicke’s sensory speech area: Impacts understanding of speech.

Question 39

What parts of the brain are supplied by the MCA?

Answer 39

The MCA supplies the lateral surface of the cerebral hemisphere, including areas responsible for speech, motor, and sensory function.

Question 40

What are common deficits caused by MCA blockage?

Answer 40

- Contralateral motor and sensory loss, especially in the face and upper limb. - Speech deficits such as aphasia (if the dominant hemisphere is affected).

Question 41

What major functional area is supplied by the PCA?

Answer 41

The primary visual cortex.

Question 42

What are the clinical deficits caused by PCA blockage?

Answer 42

Visual field defects, such as homonymous hemianopia. Memory loss, due to the hippocampus being affected.

Question 43

Which part of the limbic system is supplied by the PCA, and how does its dysfunction manifest?

Answer 43

The hippocampus, with blockage leading to memory loss.

Question 44

Clinical: What might happen if a patient has an ACA stroke affecting the contralateral lower limb?

Answer 44

Loss of motor control and sensation in the lower limb, potentially causing difficulty walking.

Question 45

If a patient cannot see objects on one side of their visual field, which artery is likely involved?

Answer 45

The posterior cerebral artery (PCA) due to involvement of the primary visual cortex.

Question 46

What is a stroke?

Answer 46

A stroke is an interruption of blood supply to parts of the brain.

Question 47

What are the two main types of strokes?

Answer 47

Ischaemic stroke – Blood supply is blocked due to a blood clot (accounts for 85% of cases). Haemorrhagic stroke – A weakened blood vessel bursts, leading to bleeding in or around the brain.

Question 48

What causes an ischaemic stroke?

Answer 48

A blockage in blood supply, often caused by a thrombus (clot formed at the site) or an embolus (clot or material traveling from elsewhere).

Question 49

What are common risk factors for ischaemic strokes?

Answer 49

Atherosclerosis Hypertension Diabetes mellitus Smoking

Question 50

What causes a haemorrhagic stroke?

Answer 50

A ruptured blood vessel, often due to: - Hypertension (chronic high blood pressure) - Aneurysms - Head trauma - Arteriovenous malformations (AVMs)

Question 51

What are the two types of haemorrhagic strokes?

Answer 51

Intracerebral haemorrhage – Bleeding directly into brain tissue. Subarachnoid haemorrhage – Bleeding into the space between the brain and the thin tissues covering it.

Question 52

What symptoms might suggest a stroke?

Answer 52

Sudden weakness or numbness, especially on one side of the body. Slurred speech or difficulty understanding speech. Vision problems in one or both eyes. Severe headache (common in haemorrhagic strokes). Loss of balance or coordination

Question 53

Why is immediate treatment critical for a stroke?

Answer 53

To minimize brain damage and prevent long-term disability or death.

Question 54

What imaging is used to differentiate between ischaemic and haemorrhagic strokes?

Answer 54

- CT Scan – Quick detection of bleeding. - MRI – Better for identifying ischemic changes in the brain.