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Anatomy · Anatomical structures

Anterior inferior cerebellar artery

a. cerebelli inferior anterior (AICA)

Anterior inferior cerebellar artery (a. cerebelli inferior anterior, AICA) is a blood vessel of the vertebrobasilar system that supplies structures of the posterior cranial fossa. It is the first major branch of the basilar artery and supplies the anteroinferior parts of the cerebellum, the lateral zone of the medulla oblongata, and the structures of the inner ear.

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Vascular territoryVertebrobasilar system
OriginLower third of the basilar artery
Key branchLabyrinthine artery (inner ear)
Stroke symptomUnilateral hearing loss
3 min readFor medical studentsUpdated 09/24/2026
Material prepared by WhiteCoat Pro editorial team based on platform study guidesReviewed by medical editor: Aulov A. A., general practitioner · 09/24/2026

Origin and location

The anterior inferior cerebellar artery arises from the lower third of the basilar artery (a. basilaris), an unpaired vessel formed by the union of the right and left vertebral arteries at the junction of the pons and medulla oblongata.

During digital subtraction angiography (DSA), blood flow in the AICA may be preserved during occlusion of the distal basilar artery because it anatomically arises proximal to the site of obstruction.

Areas of blood supply

The AICA supplies blood to the structures of the posterior cranial fossa. Its vascular territory includes:

  • Cerebellum: supplies the anterolateral parts of the inferior surface of the hemispheres, a small anteroinferior part of the hemispheres, including the flocculus and adjacent structures.
  • Brainstem (medulla oblongata): supplies the lateral zone of the medulla oblongata, specifically the area of the olivary nucleus.

Anatomical variability: The area of blood supply of the AICA is inversely related to the territory of the ipsilateral posterior inferior cerebellar artery (PICA). In some individuals, the anterior inferior cerebellar artery may supply areas of the cerebellum normally supplied by the posterior inferior cerebellar artery.

Test your knowledge on this topicExercises from the Anatomy course question bank with instant answers and explanations.

Branches of the artery

A specific branch of the AICA is the labyrinthine artery (a. labyrinthi), which may also arise directly from the basilar artery.

The labyrinthine artery enters the internal acoustic meatus (meatus acusticus internus) along with the vestibulocochlear nerve (n. vestibulocochlearis), where it divides into two groups of branches:

  • Cochlear branch (r. cochlearis) — runs along the axis of the cochlea, forms arterial glomeruli, and supplies the basilar membrane, spiral organ, and periosteum of the bony labyrinth.
  • Vestibular branches (rr. vestibulares) — supply the membranous vestibule, including the utricle, saccule, and ampullae of the semicircular ducts.

Clinical significance

Pathologies associated with the anterior inferior cerebellar artery have severe neurological consequences:

  • Ischemic stroke: Unilateral hearing loss has been described in anterior inferior cerebellar artery stroke. Cerebellar infarctions are dangerous due to the limited space in the posterior cranial fossa: even small infarcts cause a significant increase in intracranial pressure. Compression of the cerebral aqueduct or the fourth ventricle leads to obstructive hydrocephalus.
  • Aneurysms: The origin of the anterior inferior cerebellar artery is among the aneurysm locations specified in guidelines for endovascular surgery. The level of recommendation evidence is A. If endovascular surgery is not feasible, microsurgical intervention should be considered.
  • Cranial nerve compression: Vascular loops of vertebrobasilar arteries, including the AICA, may lie close to cranial nerve roots and cause irritation in areas of unmyelinated fibers.

Class and exam questions

From which artery does the AICA originate?

It arises from the lower third of the basilar artery (a. basilaris), being its first major branch at the base of the brain.

What symptom is characteristic of a stroke in the AICA territory?

In stroke within the anterior inferior cerebellar artery territory, unilateral hearing loss may occur.

How does the AICA blood supply zone depend on other arteries?

Its vascular territory is inversely related to that of the posterior inferior cerebellar artery (PICA). In some individuals, the AICA supplies areas normally supplied by the PICA.

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What else to study on this topic

  • Basilar artery (a. basilaris)
  • Posterior inferior cerebellar artery (PICA)
  • Labyrinthine artery (a. labyrinthi)
  • Blood supply to the brainstem

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Other topics in the "Anatomical Structures" section

Basilar arteryPosterior cerebral arteryPosterior inferior cerebellar arterySuperior cerebellar arteryAnterior communicating arteryAnterior spinal artery
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