Where is the basilar artery located and how is it formed?
The unpaired vessel forms at the border between the medulla oblongata and the pons through the fusion of the right and left vertebral arteries (aa. vertebrales). The a. basilaris then ascends from below upward, running along the anterior (ventral) surface of the brainstem at the level of the lower pons within the vertical basilar sulcus (sulcus basilaris pontis). The sulcus itself is anatomically formed not by pressure from the vessel, but by the pyramidal tracts projecting on either side of it.
What branches arise from the basilar artery?
As it courses, the main trunk gives off numerous branches:
- Pontine arteries (aa. pontis) are multiple penetrating vessels, subdivided into paramedian, short circumferential, and long circumferential branches, which supply the pons.
- Anterior inferior cerebellar artery (a. cerebelli inferior anterior / AICA) arises from the lower third of the basilar artery and courses toward the anteroinferior part of the cerebellum.
- Labyrinthine artery (a. labyrinthi) is a slender branch running to the internal ear through the internal acoustic meatus along with the vestibulocochlear nerve; it often arises from the anterior inferior cerebellar artery.
- Superior cerebellar artery (a. cerebelli superior) arises from the basilar artery immediately before its bifurcation, winds around the cerebral peduncle, and supplies the superior surface of the cerebellum, the superior part of the vermis, and the choroid plexus of the third ventricle.
- Posterior cerebral arteries (aa. cerebri posteriores) are the terminal branches of the basilar artery.
What is the blood supply area and function of the vessel?
Blood supply to the structures of the posterior cranial fossa comes from the vertebrobasilar system. A. basilaris supplies the ventral part of the pons and the ventral parts of the midbrain, and also gives off branches to the cerebellum. Occlusion of its penetrating branches leads to brainstem ischemia syndromes, including alternating hemiplegias.
What is the clinical significance of the basilar artery?
Atherosclerotic stenosis and occlusions have been described in the basilar artery. Saccular and fusiform aneurysms can form on the trunk of the basilar artery and in the area of its bifurcation. Basilar artery aneurysms account for about 10%: of these, 7% occur at the bifurcation and 3% on the trunk. Large aneurysms of this vessel can cause brainstem compression.
The basilar artery ends in a bifurcation into the posterior cerebral arteries and gives off cerebellar and pontine branches.
Class and exam questions
Where is the basilar artery formed?
The basilar artery (a. basilaris) is formed at the base of the brain by the union of the right and left vertebral arteries at the level of the junction between the medulla oblongata and the pons.
What terminal branches does the basilar artery form upon bifurcation?
At its bifurcation, the basilar artery divides into two terminal branches — the right and left posterior cerebral arteries (aa. cerebri posteriores).
What structures are supplied by the pontine arteries?
The pontine arteries (aa. pontis), which include paramedian, short circumferential, and long circumferential branches, supply the pons.
What else to study on this topic
- Vertebral artery (a. vertebralis)
- Posterior cerebral artery (a. cerebri posterior)
- Superior cerebellar artery (a. cerebelli superior)
- Anterior inferior cerebellar artery (AICA)
- Circle of Willis (circulus arteriosus cerebri)
Study the complete topic in the Anatomy course
This is a summary. The course covers everything tested in classes and exams.
- Complete study guide on "Basilar artery" and 1,363 other pages of the subject
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 295 video lessons by subject
Other topics in the "Anatomical Structures" section
Free video lessons: AnatomyShort lessons with study notes — no registration required.
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.