Blood Supply of the Brain

Localisation of function of the cerebral cortex | Main Anatomy Index | Monoamine pathways

Vu, D. (1998) Blood Supply of the CNS [Lecture Handouts]. University of NSW, 26 October, 1998.

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• This artery proceeds superiorly alongside the optic chiasm.
• It then bifurcates into the middle cerebral artery and anterior cerebral artery.

• Before bifurcating, it gives rise to 2 smaller branches.
• These are the anterior choroidal artery and posterior communicating artery.

• This is a long, thin artery that can be significant clinically.
• It supplies a number of structures and is not infrequently involved in cerebrovascular accidents.
• It runs posteriorly with the optic tract.

• It supplies:

1. Optic tract;
2. Lateral geniculate nucleus;
3. Optic radiation;
4. Uncus;
5. Amygdala;
6. Hippocampus;
7. Internal capsule;
8. Lenticular nucleus (globus pallidus and putamen);
9. Thalamus;
10. And the choroid plexus of the lateral ventricle (especially inferior horn).

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• This passes posteriorly, inferior to the optic tract and towards the cerebral peduncle.
• It joins the posterior cerebral artery and is one of the anastomosing branches which completes the arterial circle of Willis.

• This artery runs medially and superior to the optic nerve.
• It enters the longitudinal fissure.
• The two anterior cerebral arteries are interconnected by the anterior communicating artery near the entrance into the longitudinal fissure.

• It and its branches then arch posteriorly, following the corpus callosum.
• It supplies the medial aspect of the frontal and parietal lobes rostral to the parietooccipital sulcus.

• Along its course, it divides into 2 prominent branches:

1. The pericallosal artery, which stays immediately adjacent to the corpus callosum;
2. And the callosomarginal artery, which follows the cingulate sulcus.

• Since this artery supplies the paracentral lobule (medial aspects of the precentral and postcentral gyri), then its occlusion will cause restricted contralateral motor and somatosensory deficits.

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• This artery proceeds laterally into the lateral sulcus.
• It divides into numerous branches that supply the insula, emerge from the lateral sulcus, and spread out to supply virtually the entire lateral surface of the cerebral hemisphere.
• It importantly, also supplies the temporal pole.

• Since most of the precentral and postcentral gyri are within this area of supply, its occlusion causes major motor and somatosensory deficits.
• Also, if the left hemisphere is involved, language deficits are almost invariably found.

• Along its course towards the lateral sulcus, the middle cerebral artery gives rise to many very small branches.
• These penetrate the brain near their origin and supply deep structures of the diencephalon and telencephalon.
• These arteries are known as lateral striate (or lenticulostriate) arteries.

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• The two vertebral arteries run rostrally alongside the medulla.
• They fuse at the pontomedullary junction to form the midline basilar artery.

• Before forming the basilar artery, each vertebral artery gives rise to 3 branches:

1. The posterior spinal artery;
2. The anterior spinal artery;
3. The posterior inferior cerebellar artery (PICA).

• This runs caudally along the dorsolateral aspect of the spinal cord and supplies the posterior 1/3 of that half of the cord.

• This joins the anterior spinal artery on the other side, forming a single anterior spinal artery that runs caudally along the ventral midline of the spinal cord.
• It supplies the anterior 2/3 of the cord.

• The spinal arteries do not carry enough blood from the vertebral arteries to supply more than cervical segments and are reinforced at various points caudal to this.

• "PICA" supplies much of the inferior surface of the cerebellar hemispheres.
• It also sends branches to other structures on its way to the cerebellum.

• As it curves around the brainstem, the artery supplies the choroid plexus of the 4th ventricle and much of the lateral medulla.
• This is a uniform occurrence of the large named branches of the vertebral-basilar system on their way to their major area of supply.

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• This proceeds rostrally.
• At the level of the midbrain, it bifurcates into the 2 posterior cerebral arteries.

• Before this bifurcation, it gives rise to numerous unnamed branches.
• It also gives rise to 2 named branches:

1. The anterior inferior cerebellar artery;
2. And the superior cerebellar artery.

• "AICA" arises just rostral to the formation point of the basilar artery.

• It supplies the more anterior portions of the inferior surface of the cerebellum (e.g., the flocculus).
• It also supplies parts of the caudal pons.

• This arises just caudal to the bifurcation of the basilar artery.

• It supplies the superior surface of the cerebellum.
• It also supplies much of the caudal midbrain and rostral pons.

• The many smaller branches of the are collectively called the pontine arteries.
• They supply the remainder of the pons.

• One of these arteries, the internal auditory artery (or labyrinthine artery), that is often a branch of AICA, is functionally important as it supplies the middle ear.
• Occlusion of this artery can lead to:

1. Vertigo;
2. And ipsilateral deafness.

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• This artery curves around the midbrain and passes through the superior cistern.
• Its branches spread out to supply the medial and inferior surfaces of the occipital and temporal lobes.

• Along the way, it sends branches to the rostral midbrain and caudal diencephalon.
• It also gives rise to several posterior choroidal arteries.

• Since the primary visual cortex is located in the occipital lobe, occlusion of the posterior cerebral artery at its origin leads:

1. To visual field losses;
2. In addition to other deficits referable to the midbrain and diencephalon.

• These supply the choroid plexus of the 3rd ventricle and the body of the 4th ventricle.

• The anterior and posterior choroidal arteries form anastomoses in the vicinity of the glomus.

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• The posterior cerebral artery is connected to the internal carotid artery by the posterior communicating artery.
• This completes an arterial polygon called the circle of Willis.

• Normally, there is little or no blood flow around this circle.
• However, if one of the major vessels becomes occluded within the circle or proximal to it, the communicating arteries may allow anastomotic flow and prevent neurological damage.

• There are small arteries that arise from the arterial circle and from the major cerebral arteries.
• These central or penetrating arteries from 4 groups:

1. The anteromedial;
2. The anterolateral;
3. The posteromedial;
4. And the posterolateral.

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• These arteries supply:

1. The septal area;
2. And preoptic and anterior regions of the hypothalamus.

• This group also includes the medial striate artery (recurrent artery of Heubner) which arises from the anterior cerebral artery.
• It moves sharply backwards to supply more lateral regions:

1. The head of caudate;
2. And the anterior limb of the internal capsule.

• This is also called the lateral striate or lenticulostriate arteries.
• They supplies:

1. The head of caudate nucleus;
2. The claustrum;
3. The external capsule;
4. The putamen;
5. The lateral globus pallidus;
6. And most of the internal capsule (except ventral part of the posterior limb which is supplied by the anterior choroidal artery).

• These arteries supply:

1. The medial parts of the midbrain;
2. The anterior and medial thalamus;
3. The subthalamic regions;
4. And the middle and posterior hypothalamus.

• These are also called the thalamogeniculate arteries.
• They supply:

1. The lateral part of the midbrain;
2. And the posterior aspect of the thalamus (including the geniculate bodies, VPL and pulvinar).

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Vu, D. (1998) Blood Supply of the CNS [Lecture Handout].   UNSW, 26 October 1998.

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• The principal route of venous drainage of the brain is through a system of cerebral veins.
• These empty into the dural venous sinuses and ultimately into the internal jugular vein.

• There is also a collection of emissary veins.
• These connect the extracranial veins with the dural sinuses.
• There is also a basilar venous plexus around the base of the brain that communicates with the epidural venous plexus of the spinal cord.

• Cerebral veins are divided into superficial and deep groups.
• Generally, the superficial veins lie on the surface of the cerebral hemispheres and empty into the superior sagittal sinus.
• The deep veins drain internal structures and eventually drain into the straight sinus.

• Cerebral veins are valveless.
• They are also interconnected by numerous functional anastomoses both within a group and between the superficial and deep groups.

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• These are quite variable.
• They consist of a superior group, which empties into the superior and inferior sagittal sinuses and an inferior group, which empties into the transverse and cavernous sinuses.

• There are only 3 veins that are reasonably constant from one brain to another:

1. The superficial middle cerebral vein;
2. The superior anastomotic vein;
3. And the inferior anastomotic vein.

• This runs anteriorly and inferiorly along the lateral sulcus.
• It drains most of the temporal lobe into the cavernous sinus and the nearby sphenoparietal sinus.

• This vein is also known as the vein of Trolard.
• It typically travels across the parietal lobe and connects the superficial middle cerebral vein with the superior sagittal sinus.

• This is also known as the vein of Labbé.

• It travels posteriorly and inferiorly across the temporal lobe.
• It connects the superficial middle cerebral vein with the transverse sinus.

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• The deep veins are more constant in configuration than the superficial veins.

• This is formed at the interventricular foramen by the confluence of two smaller veins:

1. The septal vein, which runs posteriorly across the septum pellucidum;
2. And the thalamostriate vein (or terminal vein), which travels in the groove between the thalamus and the caudate nucleus.

• Near the interventricular foramen, the thalamostriate vein receives the choroidal vein.
• This vein is a tortuous vessel that drains the choroid plexus of the body of the lateral ventricle.

• Immediately after forming, the internal cerebral vein bends sharply in a posterior direction.
• This bend is called the venous angle.

• The paired internal cerebral veins proceed posteriorly through the transverse cerebral fissure.

• The paired internal cerebral veins fuse in the superior cistern to form the unpaired great cerebral vein (or vein of Galen).
• The vein turns superiorly and joins the inferior sagittal sinus to form the straight sinus.

• Along its course, it receives the basal veins (of Rosenthal).

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