Neuroanatomy, Brain, Arteries, Anterior Inferior Cerebellar

The anterior inferior cerebellar artery (AICA) is one of the most vital arteries. It supplies structures of the posterior fossa. The posterior fossa is bounded by the foramen magnum and tentorium cerebelli and houses structures including the medulla, pons, midbrain, and cerebellum. Arterial supply to these structures are branches of the vertebrobasilar circulation. The vertebral arteries typically arise from the subclavian arteries bilaterally. They ascend and enter the cranium through the foramen magnum where they fuse at the caudal border of the pons to form the basilar artery. Major branches from the vertebral arteries include the anterior spinal artery which supplies the medial medulla, the posterior inferior cerebellar arteries (PICA) which supply the rostral lateral medulla, and the posterior spinal artery (PSA) which supplies the caudal medulla. The anterior inferior cerebellar artery is one of the major branches of the basilar artery. It is the most caudal branch and arises from the lateral wall of the caudal third of the basilar artery. Anterior inferior cerebellar artery usually originates as a single trunk and supplies the ventral and inferior surface of the cerebellum and the lower lateral pons. Anterior inferior cerebellar artery courses laterally and posteriorly, commonly bifurcating into the superior and inferior trunk at the pontomedullary junction near where the facial and vestibulocochlear nerves exit the brain stem. The length of the anterior inferior cerebellar artery can be divided into four segments including the anterior pontine (close to the abducent nerve), lateral pontine (close to the facial and vestibulocochlear nerves), floccu peduncular, and cortical segments. The lateral pontine segments can be further divided into pre-meatal, meatal, and postmeatal segments. The segments are named because of their relationship with the internal auditory meatus. Other arteries that branch off the basilar artery includes the pontine arteries which supply both the upper and lower medial pons. The labyrinthine artery is also called the internal auditory artery (in most cases usually branched from the anterior inferior cerebellar artery). It supplies the labyrinth and cochlea of the inner ear. The superior cerebellar arteries branch off the basilar artery immediately before it bifurcates and supplies the rostral pons, caudal midbrain and superior part of the cerebellum. Finally, the posterior cerebral artery (PCA) is the last branch of the basilar artery, and it becomes part of the Circle of Willis. Some posterior cerebral artery branches supply the midbrain, thalamus, temporal lobes, medial and inferior occipital lobes of the cerebral cortex[1][2][3].