Blood Supply of the Brain
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Localisation
of function of the cerebral cortex | Main Anatomy
Index | Monoamine pathways
Last updated 30 March 2006
Blood Supply of the Brain
Vu, D. (1998) Blood Supply of the CNS [Lecture Handouts]. University of NSW, 26
October, 1998.
Quick links:
Arterial Supply
Internal Carotid System
This artery proceeds superiorly alongside the optic chiasm.
It then bifurcates into the middle cerebral artery
and anterior cerebral artery.
Anterior Choroidal 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.
- Optic tract;
- Lateral geniculate
nucleus;
- Optic radiation;
- Uncus;
- Amygdala;
- Hippocampus;
- Internal capsule;
- Lenticular nucleus (globus pallidus
and putamen);
- Thalamus;
- And the choroid plexus of the lateral ventricle
(especially inferior horn).
Posterior Communicating Artery
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.
Anterior Cerebral Artery
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.
- Along its course, it divides into 2 prominent branches:
- The pericallosal artery, which stays immediately
adjacent to the corpus callosum;
- 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.
Middle Cerebral Artery
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.
Vertebral-Basilar System
Vertebral Arteries
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:
- The posterior spinal artery;
- The anterior spinal artery;
- The posterior inferior cerebellar artery
(PICA).
Posterior Spinal Artery
This runs caudally along the dorsolateral
aspect of the spinal cord and supplies the posterior 1/3 of
that half of the cord.
Anterior Spinal Artery
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.
Posterior Inferior Cerebellar Artery
"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.
Basilar Artery
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:
- The anterior inferior cerebellar artery;
- And the superior cerebellar artery.
Anterior Inferior 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.
Superior Cerebellar Artery
This arises just caudal to the bifurcation of the basilar artery.
Internal Auditory Artery
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:
- Vertigo
;
- And ipsilateral deafness.
Posterior Cerebral Artery
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.
- Since the primary visual cortex is located in the occipital lobe, occlusion of the
posterior cerebral artery at its origin leads:
- To visual field losses;
- In addition to other deficits referable to the midbrain
and diencephalon.
Posterior Choroidal Arteries
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.
The Circle of Willis
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:
- The anteromedial;
- The anterolateral;
- The posteromedial;
- And the posterolateral.
Anteromedial Group
These arteries supply:
- The septal area;
- 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:
- The head of caudate;
- And the anterior limb of the internal capsule.
Anterolateral Group
This is also called the lateral striate or lenticulostriate arteries.
They supplies:
- The head of caudate
nucleus;
- The claustrum;
- The external capsule;
- The putamen;
- The lateral globus
pallidus;
- And most of the internal capsule (except
ventral part of the posterior limb which is supplied by the anterior choroidal artery).
Posteromedial Group
These arteries supply:
- The medial parts of the midbrain;
- The anterior and medial thalamus;
- The subthalamic regions;
- And the middle and posterior hypothalamus.
Posterolateral Group
These are also called the thalamogeniculate arteries.
They supply:
- The lateral part of the midbrain;
- And the posterior aspect of the thalamus (including the geniculate bodies, VPL and
pulvinar).
Blood Supply of Important Regions
Vu, D. (1998) Blood Supply of the CNS [Lecture Handout]. UNSW, 26 October 1998.
Venous Drainage
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.
Superficial Veins
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:
- The superficial middle cerebral vein;
- The superior anastomotic vein;
- And the inferior anastomotic vein.
Superficial Middle Cerebral 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.
Superior Anastomotic Vein
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.
Inferior Anastomotic Vein
This is also known as the vein of Labbé.
Deep Veins
The deep veins are more constant in configuration than
the superficial veins.
Internal Cerebral Vein
This is formed at the interventricular foramen by the confluence of two smaller veins:
- The septal vein, which runs posteriorly across the
septum pellucidum;
- 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.
Great Cerebral Vein
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).