Anterior cerebral artery
The blood supply to the cerebral hemispheres is based on major vessels that are the terminal branches of the internal carotid artery (a. carotis interna).
The anterior cerebral artery (a. cerebri anterior) runs forward and toward the medial plane, lying directly above the optic nerve. It then enters the longitudinal fissure of the brain and extends along the medial surface of the hemisphere. The vessel curves around the genu of the corpus callosum (genu corporis callosi) and proceeds toward the occipital lobe.
Its basin includes:
- Anterior central arteries (aa. centrales anteromediales) — supply the basal nuclei, including the internal capsule and caudate nucleus.
- Anterior communicating artery (a. communicans anterior) — connects both anterior cerebral arteries at the level of the optic chiasm.
- Postcommunicating part (a. pericallosa) — gives rise to arteries supplying the medial surface of the frontal lobe (a. frontobasalis medialis), the branch along the corpus callosum (a. callosomarginalis), frontal branches, the branch to the paracentral lobule (motor representation of the leg), and the precuneus.
In general, this artery supplies blood to the medial segments of the frontal and parietal lobes, as well as the upper part of the postcentral and precentral gyri.
Middle cerebral artery
The middle cerebral artery (a. cerebri media) is the largest branch of the internal carotid artery. Its path runs deep into the lateral sulcus (sulcus lateralis), where it divides into sphenoidal (pars sphenoidalis), insular (pars insularis), and cortical (pars corticalis) parts. This vessel supplies most of the lateral surface of the hemispheres, including Broca's and Wernicke's speech centers, as well as the cortical areas of motor and sensory control for the face and hand.
Key branches:
- Central thalamostriate arteries — penetrate deeply through the anterior perforated substance, supplying blood to the putamen (putamen), internal capsule, and caudate nucleus.
- Frontobasal arteries — head toward the inferior plane of the frontal lobe.
- Temporal arteries (anterior, middle, and posterior) — supply the temporal lobe.
- Arteries of the central sulci — run to the pre- and postcentral gyri.
- Parietal arteries — supply the parietal region.
- Angular gyrus artery (a. gyri angularis) — forms an anastomosis with the posterior cerebral artery territory.
Choroid and posterior communicating arteries
In addition to the main trunks, other important vessels arise from the posterior surface of the internal carotid artery.
The anterior choroidal artery (a. choroidea anterior) courses laterally, running parallel to the cerebral peduncle. It penetrates the substance of the temporal lobe, ultimately reaching the choroid plexus of the lateral ventricle. Along its course, it gives off branches to the globus pallidus, amygdala, optic tract, internal capsule, caudate nucleus, and lateral geniculate body.
The posterior communicating artery (a. communicans posterior) runs posteriorly, connecting the internal carotid artery with the posterior cerebral artery. It supplies the optic chiasm, hypothalamus (including the tuber cinereum), as well as midbrain structures—the red nucleus and substantia nigra.
Arterial circle of the cerebrum (circle of Willis)
A unique structure at the base of the brain is the arterial circle of the cerebrum (circulus arteriosus cerebri). It is a closed system of anastomoses that plays a critical role in the reliability of cerebral blood flow.
How it is formed:
- Anteriorly: the right and left anterior cerebral arteries are connected via the a. communicans anterior.
- Laterally: the internal carotid artery is connected to the posterior cerebral artery via the a. communicans posterior.
- Posteriorly: branches of the basilar artery (a. basilaris) participate in forming the circle.
The main significance of this circle is the formation of collateral blood flow. In case of stenosis or occlusion of a major artery, blood can flow from the opposite side, compensating for the deficiency.
Clinical significance:
- The a. cerebri media territory is the most frequent location of ischemic stroke. Lesions result in aphasia and hemiparesis of the arm and face.
- The ophthalmic artery (a. ophthalmica) is the first intracranial branch and serves as an important connecting link between the internal and external carotid artery systems.
Briefly: answers to topical questions
What are the functions of the ophthalmic artery?
The ophthalmic artery (a. ophthalmica) supplies blood to the eyeball and also provides a connection between the internal and external carotid artery systems. By giving off numerous branches, it performs the following functions:
- Lacrimal artery (a. lacrimalis) — to the lacrimal gland and eyelids.
- Central retinal artery (a. centralis retinae) — supplies the retina.
- Short and long posterior ciliary arteries (aa. ciliares posteriores breves et longae) — to the choroid and ciliary body.
- Muscular branches (aa. musculares) — supply the rectus and oblique muscles of the eye.
- Posterior and anterior ethmoidal arteries (a. ethmoidalis posterior, a. ethmoidalis anterior) — supply the mucous membrane of the ethmoidal labyrinth, sphenoid sinus, nasal cavity, and dura mater of the anterior cranial fossa.
- Supraorbital and supratrochlear arteries (a. supraorbitalis, a. supratrochlearis) — supply the skin of the forehead, the frontal belly of the m. occipitofrontalis, and the upper eyelid.
- Dorsal nasal artery (a. dorsalis nasi) — to the dorsum of the nose.
What structures do the central thalamostriate arteries supply?
The central thalamostriate arteries (aa. centrales anterolaterales or aa. thalamostriatae) supply a number of deep brain structures. Penetrating through the anterior perforated substance, they supply the following structures:
- Caudate nucleus — receives blood supply from the central arteries.
- Internal capsule — is supplied by the thalamostriate branches.
- Putamen (putamen) — is also supplied by these vessels.
To memorize the composition of the circle of Willis, imagine a hexagon at the base of the brain: anteriorly, two anterior cerebral arteries are closed by the anterior communicating artery; laterally run the posterior communicating arteries; and the posterior base is formed by the posterior cerebral arteries.
Class and exam questions
Which artery supplies the paracentral lobule?
This region, containing the motor representation of the leg, is supplied by a branch of the anterior cerebral artery — r. paracentralis.
Damage to which vessel most commonly causes aphasia?
Speech impairment (aphasia) along with hemiparesis of the arm and face typically develops during an ischemic stroke in the middle cerebral artery territory, which supplies Broca's and Wernicke's centers.
What does the anterior choroidal artery supply?
It supplies blood to the caudate nucleus, globus pallidus, internal capsule, amygdala, optic tract, and lateral geniculate body.
What is the function of the Circle of Willis?
It creates a closed ring of collateral circulation at the base of the brain. In the event of occlusion of one of the vessels, this network helps compensate for the blood deficit.
What else to study on this topic
- Cortical and central branches of the middle cerebral artery
- Anastomosis of the ophthalmic artery with the external carotid artery
- Topography of the insular and sphenoidal parts of the middle cerebral artery
- Detailed blood supply of the internal capsule and basal nuclei
- Variations in the structure of the cerebral arterial circle
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