Anterior Inferior Cerebellar Artery

The Anterior Inferior Cerebellar Arteries (AICAs) typically arise from the lower half of the basilar artery (BA), most commonly from a single trunk. The AICA is divided into four segments: the anterior pontine (a1), the lateral pontine (a2), the flocculopeduncular (a3), and the cortical (a4) segments.

• The A1 segment extends from its origin to the midpoint of the inferior olive.
• The A2 segment extends from the inferior olive to the flocculus and includes several branches: the labyrinthine, the subarcuate, the cerebellosubarcuate, and recurrent perforating arteries.
• The A3 segment extends from the flocculus to the cerebellopontine fissure.
• The A4 segment is the portion of the vessel distal to the cerebellopontine fissure.