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Neuroanatomy > Blood Supply to the Brain > Flashcards

Blood Supply to the Brain Flashcards

1
Q

What 2 arteries is the blood supply to the brain derived from?

How do these arteries enter the skull?

A

Internal carotid artery:

  • this is a branch of the common carotid artery
  • it enters the skull via the carotid canal

Vertebral artery:

  • this is a branch of the subclavian artery
  • it enters the skull via the foramen magnum
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2
Q

What is the difference in how the subclavian artery arises on the right and left sides?

A
  • the left subclavian artery (and common carotid) arise directly from the arch of the aorta
  • on the right side, the brachiocephalic trunk arises from the arch of the aorta
  • this then divides into the right subclavian and common carotid arteries
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3
Q

Where does the vertebral artery originate from?

How does it enter the cranium and what does it fuse once it is there?

A
  • it is the first branch of the subclavian artery
  • it enters the transverse foramen of C6 and ascends through the transverse foramina of higher vertebrae
  • it enters the cranium via foramen magnum
  • at the level of the pontomedullary junction, the 2 vertebral arteries fuse to form the basilar artery
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4
Q

Where does the posterior cerebral artery arise from?

A

the posterior cerebral artery arises from the basilar artery as it bifurcates

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5
Q

Where do the anterior and middle cerebral arteries arise from?

A
  • the internal carotid artery terminates by dividing into the anterior and middle cerebral arteries
  • the ACA is a smaller branch than the MCA
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6
Q

What is the role of the anterior and posterior communicating arteries?

A

they connect the cerebral arteries

Anterior communicating artery:

  • connects the left and right anterior cerebral arteries

Posterior communicating artery:

  • connects the middle cerebral artery with the posterior cerebral artery on each side
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7
Q

What are the 3 cerebellar arteries and where do they arise from?

A

Posterior inferior cerebellar artery (PICA):

  • this is a branch of the vertebral artery

Anterior inferior cerebellar artery (AICA):

  • this arises at the point where the 2 vertebral arteries fuse to form the basilar artery

Superior cerebellar artery:

  • this arises from the basilar artery as it bifurcates at the level of the pontomesencephalic junction
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8
Q

Where does the middle cerebral artery arise from?

How does it travel in the brain and which regions does it supply?

A
  • it is the larger of the 2 terminal branches of the internal carotid artery
    • the other branch is the anterior cerebral artery
  • it passes laterally to supply blood to the lateral convexity of the cerebral hemisphere, including parts of the temporal, parietal, frontal and occipital lobes
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9
Q

What are the branches of the middle cerebral artery?

A
  1. lenticulostriate branches
  2. orbitofrontal artery
  3. pre-central (pre-Rolandic) and central (Rolandic) branches
  4. anterior & posterior parietal arteries
  5. angular artery
  6. anterior, middle & posterior temporal arteries
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10
Q

What is the role of the lenticulostriate branches of the MCA?

A
  • these are a group of small arteries that supply the putamen, caudate nucleus and anterior limb of the internal capsule
  • they are the first branches of the MCA
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11
Q

What is supplied by the orbitofrontal artery of the MCA?

A
  • it supplies part of the frontal lobe
  • it supplies the orbital gyri and the inferior frontal gyrus
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12
Q

What is supplied by the pre-central (pre-Rolandic) and central (Rolandic) arteries?

A
  • these arteries supply different regions of the frontal lobe
  • the Rolandic branch runs alongside the central sulcus
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13
Q

What is supplied by the angular artery?

A
  • this supplies the angular gyrus
  • this is part of the inferior parietal lobule that has a role in language and number processing, memory and reasoning
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14
Q

How can the middle cerebral artery be divided?

A

It can be divided into 4 anatomical segments (M1-M4)

  • M1 - horizontal segment
  • M2 - insular segment
  • M3 - opercular segment
  • M4 - cortical segment
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15
Q

Where does the M1 (horizontal) segment of the MCA run to and from?

A
  • it runs from the origin at the internal carotid artery to the bifurcation of the MCA at the limen insulae
  • the limen insulae is located just as the MCA passes out through the lateral sulcus by the insula
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16
Q

Where does the M2 (insular) segment of the MCA run to and from?

A
  • it runs from the bifurcation at the limen insulae to the cortical branches
  • there are 2 branches formed at the limen insulae - one runs superiorly and one runs inferiorly
  • both of these branches run along the insula
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17
Q

Where do the M3 (opercular) and M4 (cortical) segments of the MCA run?

A
  • M3 describes the opercular branches that run within the lateral fissure
  • M4 describes the cortical branches that emerge from the lateral fissure onto the surface of the cortex
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18
Q

Which branches arise from the M1 (horizontal) segment of the MCA?

A
  • lenticulostriate arteries
  • anterior and polar temporal arteries
  • uncal artery
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19
Q

Which branches arise from the superior and inferior terminal branches of the M2-M4 segments of the MCA?

A

Superior terminal branch:

  • orbitofrontal artery
  • pre-Rolandic artery
  • Rolandic artery

Inferior terminal branch:

  • anterior & posterior parietal arteries
  • angular artery
  • anterior, middle & posterior temporal arteries
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20
Q

In general, what territories are supplied by the MCA?

A
  • majority of the lateral surface of the hemispheres
  • internal capsule
  • basal ganglia
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21
Q

Where does the anterior cerebral artery arise from it?

How does it travel in the brain?

A
  • it is the smaller of the 2 terminal branches of the internal carotid artery
  • it passes anteromedially towards the midline in the longitudinal fissure
  • it then passes anterior to the genu of the corpus callosum and then curves posteriorly
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22
Q

Which structures are supplied by the anterior cerebral artery?

A
  • it supplies blood to the medial aspect of the hemisphere, including parts of the frontal and parietal lobes
  • it supplies the precentral and postcentral gyri
  • it supplies the olfactory bulb and tract, anterior hypothalamus, parts of the caudate nucleus, internal capsule and putamen
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23
Q

What are the 2 major branches of the ACA?

A
  1. callosomarginal artery
  2. pericallosal artery
24
Q

What is supplied by the callosomarginal artery?

A
  • the paracentral lobule and portions of the cingulate gyrus
25
Q

What is supplied by the pericallosal artery?

A
  • this continues along the dorsal margin of the corpus callosum to supply the precuneus
  • this is part of the parietal lobe that is caudal to the paracentral lobule
26
Q

What are the 3 segments of the anterior cerebral artery?

A

A1:

  • from origin of ACA at internal carotid artery to the anterior communicating artery

A2:

  • from the anterior communicating artery to the origin of the callosomarginal artery

A3:

  • this runs distal to the callosomarginal artery and is also the pericallosal artery
27
Q

What are the 2 main branching patterns of the anterior cerebral artery?

A
  • A2 gives off the callosomarginal artery and continues as the pericallosal artery

Cortical branches arise from the callosomarginal artery

  • The callosomarginal artery is absent

Cortical branches arise directly from the pericallosal artery

(Cortical branches go over by about 1cm onto the lateral aspect of the brain)

28
Q

Why can occlusion of the anterior cerebral artery lead to paralysis and loss of sensation of the contralateral leg?

A
  • the ACA supplies the precentral gyrus, which processes sensory information from the contralateral leg
  • it also supplies the postcentral gyrus, which initiates motor control of the contralateral leg
  • occlusion of the ACA leads to loss of motor control (paralysis) and loss of sensation of the contralateral leg
29
Q

What are the main branches of the anterior cerebral artery?

A
  1. anterior communicating artery
  2. medial striate artery (recurrent artery of Heubner)
  3. orbital branches
  4. frontopolar branches
30
Q

What is the function of the anterior communicating artery?

What arises from this vessel?

A
  • it connects the right and left anterior cerebral arteries at the level of the optic chiasm
  • a group of small arteries arise from the anterior communicating and anterior cerebral arteries and penetrate the brain tissue perpendicularly

these supply blood to the anterior hypothalamus - including preoptic and suprachiasmatic areas

31
Q

Where do intracranial aneurysms commonly occur in the anterior circulation?

What can this present with?

A
  • at the junction between the anterior communicating artery and anterior cerebral artery
  • these aneurysms can cause visual defects due to their proximity to the optic chiasm
32
Q

What is supplied by the medial striate artery (recurrent artery of Heubner)?

A
  • anteromedial part of the head of the caudate nucleus
  • parts of internal capsule
  • putamen
  • septal nuclei

it arises from the ACA at the level of the optic chaism and penetrates the perforated substance

33
Q

What is supplied by the orbital and frontopolar branches of the ACA?

A

Orbital branches:

  • supply the orbital and medial surfaces of the frontal lobe

Frontopolar branches:

  • supply the medial aspects of the frontal lobe
  • (Both orbital and frontopolar branches arise from the A2 segment of the ACA)*
34
Q

What is the origin of the posterior cerebral artery?

How does it travel from its origin?

A
  • it is formed from the terminal bifurcation of the basilar artery
  • it courses around the midbrain towards the dorsal (posterior) aspect of the brain
35
Q

What is supplied by the posterior cerebral artery?

A
  • most of the midbrain
  • thalamus
  • subthalamic nucleus
36
Q

How can the posterior cerebral artery be divided in to 4 segments?

A

P1:

  • from origin at bifurcation of basilar artery to origin of posterior communicating artery

P2:

  • from posterior communicating artery to the quadrigeminal cistern at the posterior border of the lateral midbrain
    • can be divided into P2A and P2P segments

P3:

  • from quadrigeminal cistern to the origin of the calcarine and parieto-occipital arteries

P4:

  • this describes the terminal branches of the PCA - calcarine and parieto-occipital
37
Q

What are the 4 major branches of the posterior cerebral artery?

What do they supply?

A
  • anterior temporal branches
  • posterior temporal branches
  • parieto-occipital branches

These supply the temporal lobes and medial /inferior occipital lobe

  • calcarine branches

These supply the primary visual cortex

38
Q
A
39
Q

What small arteries can arise from the P2 segment of the PCA to supply the midbrain?

A

Quadrigeminal arteries

  • these supply the inferior and superior colliculi on the dorsal aspect of the midbrain
40
Q

What is meant by the vertebro-basilar circulation and what does it supply?

A
  • this system includes the 2 vertebral arteries, the basilar artery and their branches
  • it supplies the medulla, pons, midbrain and cerebellum
41
Q

At the level of the medulla, which 3 branches are given off by the vertebral artery?

A
  • anterior spinal artery
  • posterior spinal artery
  • posterior inferior cerebellar artery (PICA)
42
Q

What regions / structures are supplied by the PICA?

A

Regions of the lateral medulla:

  • spinothalamic tract
  • dorsal & ventral spinocerebellar tracts
  • descending sympathetic tract
  • descending tract of trigeminal nerve (V)
  • nucleus ambiguus

Cerebellum:

  • region of the vermis
  • inferolateral surface of cerebellum
43
Q

What syndrome results drom occlusion of the PICA?

A

Lateral medullary (Wallenberg’s) syndrome

  • there is damage to the lateral medulla in the region supplied by the PICA
  • damage to the nucleus ambiguus leads to dysphonia, dysarthria and dysphagia
    • this is due to the nucleus ambiguus innervating the laryngeal muscles
  • there is also loss of coordination / balance (ataxia) and vertigo
  • there is loss of contralateral P&T sensation if lateral STT is involved
  • sensory disturbances from contralateral side of the body and ipsilateral side of the face
44
Q

What are the branches of the basilar artery?

A
  • anterior inferior cerebellar artery (AICA)
  • labyrinthine artery
  • pontine arteries
  • superior cerebellar artery (SCA)
  • posterior cerebral artery
45
Q

What is supplied by the AICA?

A
  • ventral and inferior surface of the cerebellum
  • some of the lateral surface of the pons
46
Q

What is supplied by the superior cerebellar artery?

A
  • it supplies the rostral pons, caudal midbrain and superior surface of the cerebellum, including:
  1. portions of the superior and middle cerebellar peduncles
  2. medial & lateral lemniscus
  3. part of spinal trigeminal nucleus & tract
  4. spinothalalmic tract
47
Q

What is surrounded by the circle of Willis?

What forms this structure?

A
  • it surrounds the optic chiasm and infundibulum of the pituitary gland
  • it is formed by the anastomosis of the branches of the internal carotid artery and the terminal branches of the basilar artery
48
Q

What is the clinical importance of the circle of Willis?

A

if the blood supply in either the internal carotid arteries or vertebro-basilar system is compromised, the circle of Willis provides a collateral blood supply

49
Q

What are striate arteries and where do they arise from?

A
  • they are small arteries that supply the deep tissue of the brain
  • they arise from the posterior cerebral artery and both the anterior & posterior communicating arteries
50
Q

What is a berry aneurysm?

Where are they most likely to rupture?

A
  • a condition in which weakness in the wall of a cerebral artery or vein causes a localised dilation or ballooning of the blood vessel
  • an aneurysm occurring in the posterior circulation is more likely to rupture
    • this includes the basilar artery, vertebral artery & posterior communicating artery
51
Q

What are some causes of berry aneurysms?

A
  • connective tissue disorders
  • polycystic kidney disease
  • arteriovenous malformations
  • untreated hypertension
  • tobacco smoking
  • cocaine & amphetamines
  • head trauma
  • heavy caffeine intake
  • intravenous drug use
  • infection of the arterial wall from bacteraemia
52
Q

What are the symptoms of berry aneurysm?

A
  • typically, they are asymptomatic until they rupture and then may cause:
  1. sudden and unusually severe headache
  2. nausea & vomiting
  3. vision impairment
  4. loss of consciousness
  5. no symptoms at all
53
Q

What type of haemorrhage can a ruptured berry aneurysm lead to and what are the symptoms of this?

A

subarachnoid haemorrhage

  • typically presents with a sudden onset “thunderclap” headache, as well as:
  1. nausea & vomiting
  2. drowsiness, confusion & loss of consciousness
  3. visual abnormalities
  4. meningism
  5. dizziness
54
Q

Where, specifically, is CSF produced and how is this related to blood supply?

A
  • CSF is produced by the choroid plexus within the ventricular system
  • CSF production is an active process that requires a blood supply
  • the lateral ventricle produces the most CSF as it is the largest and contains the greatest amount of choroid plexus
55
Q

What is the blood supply to the lateral ventricle and IIIrd ventricle?

A
  • anterior choroidal artery

this is a branch of the middle cerebral artery (MCA) at the junction between the MCA and ICA

  • lateral posterior choroidal artery
  • medial posterior choroidal artery

these are branches of the posterior cerebral artery (P2)

56
Q

What is the blood supply to the IVth ventricle?

A
  • anterior inferior cerebellar artery (AICA)
  • posterior inferior cerebellar artery (PICA)

Neuroanatomy (16 decks)

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