Arterial blood supply of the brain

Question 1

What are the vessels supplying the brain

Answer 1

Supplied by the branches of the internal carotid and vertebral arteries.

Question 2

What covers the blood vessels of the brain?

Answer 2

They are covered by a lengthening of pia mater.

Question 3

What do the end branches of the internal carotid and vertebral arteries supply?

Answer 3

Superficial cortical branches supply grey matter.
Perforating branches supply subcortical nuclei.

Question 4

What is the Circle of Willis?

Answer 4

The internal carotid and vertebral arteries anastomoses form this.
It is around the optic chiasma and infundibulum

Question 5

Describe the formation of the Circle for Willis.

Answer 5

The basilar artery divides into left and right posterior cerebral arteries.
Each posterior cerebral artery receives a posterior communicating artery from the internal carotid artery.
Each internal carotid artery gives an anterior cerebral artery.
The anterior communicating artery connects the two.

Question 6

What is the clinical significance of the Circle of Willis?

Answer 6

This allows anastomotic circulation between the two sides of a block.
The most common type of subarachnoidal aneurysms occurs here, more frequently carotid part.
This is because the tunica media is the weakest where the branches are given off.

Question 7

What is the blood supply of the cerebral hemisphere?

Answer 7

1. Anterior cerebral artery
2. Middle cerebral artery
3. Posterior cerebral artery
4. Anterior choroidal artery (doesn’t supply cortex)

Question 8

Role of the blood supply of the brain in forming the blood-brain barrier.

Answer 8

Capillaries of the brain (and spinal cord) don’t have fenestration
They have a lot of tight junctions
This helps form the blood-brain barrier.

Question 9

List the areas not covered by the blood-brain barrier.

Answer 9

Posterior pituitary
Median eminence of the hypothalamus
Pineal gland

Question 10

Formation and course of the middle meningeal artery.

Answer 10

The largest and most direct branch of the internal carotid artery
Passes in the lateral sulcus supplying the insular cortex
Its branches emerge here supplying an area around the lateral sulcus with the width of a single gyrus.

Question 11

Supply of the middle meningeal artery.

Answer 11

The opposite half of the body without a leg foot and perineum
Auditory and speech areas.

Question 12

Formation and course of the Anterior Cerebral Artery.

Answer 12

A branch from each of the internal carotid arteries leaves the anterior perforated substance.
It passes above the optic nerve
Each anterior cerebral artery is connected by the anterior communicating artery.

Question 13

Supply of the anterior cerebral artery.

Answer 13

The orbital surface of the frontal lobe
The whole medial surface of the hemisphere above the corpus callosum up to the Pareto–occipital sulcus.
The motor and sensory areas of the opposite leg, foot, perineum
Micturition and defecation centers.

Question 14

Formation and course of the Posterior cerebral artery

Answer 14

Curls back around the cerebral peduncle
Extends till parieto – occipital sulcus

Question 15

Supply of the Posterior cerebral artery.

Answer 15

Cerebral peduncle
Optic tract
Inferomedial surface of temporal and occipital lobes (Infero temporal gyrus, a strip of cortex on its lateral surface)
Some small branches supply the choroid plexus as well.

Question 16

The course of the anterior choroidal artery

Answer 16

Passes below the optic tract enter the inferior horn of the lateral ventricle.

Question 17

Supply of the anterior choroidal artery.

Answer 17

Supplies the choroid plexus
Optic tract
Optic radiation
Lateral geniculate body
The posterior part of the internal capsule
Basal nuclei and limbic system

Question 18

What does the middle cerebral artery supply

Answer 18

The middle cerebral artery gives small lateral branches to the internal capsule and anterior perforated substance and thalamus and basal nuclei.
Medial striate artery is usually a branch of middle cerebral artery.

Question 19

In the blood supply of the brain, what is the most common artery to be ruptured or occluded?

Answer 19

Charcot’s artery of cerebral hemorrhage is the largest and most common to rupture or be occluded

Question 20

What is the blood supply of the posterior perforated substance

Answer 20

Branches from the posterior cerebral artery pierce the posterior perforated substance

Question 21

Clinical symptoms of artery blocks: Anterior cerebral

Answer 21

Contralateral weakness and sensory loss (Mainly leg, foot, perineum)

Question 22

Clinical symptoms of artery blocks: Middle cerebral

Answer 22

Contralateral hemiplegia and hemianesthesia (with aphasia if the lesion is left-sided)

Question 23

Clinical symptoms of artery blocks: Posterior cerebral

Answer 23

Contralateral hemianopia and hemianesthesia

Question 24

Clinical symptoms of artery blocks: Anterior choroidal

Answer 24

Contralateral hemianopia and hemianesthesia, with some hemiplegia

Question 25

Explain Extradural Hemorrhages

Answer 25

Damage to vessels running in epidural space/ within the two layers of the dura mater
arteria blood accumulates between the two Dural layers limited by the attachments of the Dural layers to the
Pressure increases rapidly in the brain because of arterial blood accumulation.

Question 26

What is the artery most commonly responsible for extradural hemorrhages?

Answer 26

Anterior branch of middle meningeal artery damage is responsible most of the time.
This artery moves just deep to the pterion of the skull which is viable to damage on trauma.

Question 27

What is the CT presentation of extradural hemorrhages

Answer 27

blood is filled only on a contained space which forms a lens shape on the CT

Question 28

Explain Subdural Hemorrhages.

Answer 28

Accumulation of blood between meningeal layers of sura mater and arachnoid layer.
Venous blood accumulates so an increase in pressure happens slowly so symptoms also appear slowly when compared with epidural hemorrhages.

Question 29

what is the most common blood vessel responsible for subdural hemorrhages?

Answer 29

Happens due to the rupture of the bridging veins like the superior cerebral vein at their fixed place to the dura.

Question 30

CT presentation of subdural hemorrhages.

Answer 30

Forms a crescent-shaped hematoma.

Question 31

Symptoms of epidural and subdural hemorrhages.

Answer 31

Symptoms of epidural and subdural hemorrhages are common to each other.
The only difference is the time taken for the symptoms to appear.
Symptoms of drowsiness, low heart rate, and headache will appear.

Question 32

Describe Subarachnoid Hemorrhages.

Answer 32

Accumulation of blood deep to arachnoid mater.
Caused by aneurysms of the circle of Willis.
Aneurysms lead to rupture of the vessels and eventually blood is contaminated with CSF.
Symptoms are; severe headache, nausea, vomiting

Question 33

Blood Supply of the spinal cord

Answer 33

A single anterior spinal artery
Couple of posterior spinal arteries
Segmental arteries/ radicular arteries

Question 34

The course of the anterior spinal artery.

Answer 34

runs the whole length of the spinal cord longitudinally even though it may be deficient in some places like in the thoracic region.
Lies on the median fissure.

Question 35

Formation of the anterior spinal artery.

Answer 35

given off by vertebral artery

Question 36

Supply of the anterior spinal artery

Answer 36

supplies the anterior 2/3 of the spinal cord excluding the posterior grey columns

Question 37

Formation of the posterior spinal artery.

Answer 37

arise from the vertebral artery or posterior inferior cerebellar artery

Question 38

Supply of the posterior spinal artery.

Answer 38

Supplies Posterior 1/3 of spinal cord. Runs behind the posterior nerve rootlets.

Question 39

course of the posterior spinal artery.

Answer 39

There are a couple of arteries on the left and right side running longitudinally.

Question 40

What are the Segmental arteries on radicular arteries?

Answer 40

arises from the neighboring vessels like lumbar arteries, intercostal arteries, lateral sacral arteries
These arteries form an anastomotic network with the spinal arteries on the surface of the spinal cord deep to the pia mater

Question 41

What is the largest radicular artery?

Answer 41

Out of these vessels, the largest “arteria radicularis magna” arises from a lower intercostal or upper lumbar branch on the left side.

Question 42

What are pial arteries?

Answer 42

Radicular arteries form an anastomosis.
This anastomosis supplies pial arteries which supply the periphery of the spinal cord.

Question 43

Arrangement of the fibers in the lateral corticospinal and anterolateral tracts in the spinal cord.

Answer 43

Ascending and descending tracts of the spinal cord are laminated within the spinal cord in such a way that with respect to lateral corticospinal and anterolateral tracts sacral fibers lie nearer to the surface.

Question 44

Describe Sacral Sparing.

Answer 44

Pial arteries branched off from anastomosis supplies surface sacral fibers.
So even in ischaemic conditions of the major spinal arteries still blood supply to the sacral fibers is retained excluding the pathological symptoms from the sacral region.
This phenomenon is known as sacral sparing.
In anterior spinal artery ischemia posterior grey column is preserved hence retaining the sensation of touch altogether with the sacral sensations of anterolateral grey columns.

Question 45

Venous drainage of the spinal cord.

Answer 45

The venous network drains to the internal vertebral venous plexus and from there on to the external vertebral venous plexus.
Then they drain to the segmental veins of the lateral sacral, vertebral, azygos, and lumbar.
At the foramen magnum venous network communicates with the ones of the medulla oblongata.