Posterior Inferior Cerebellar Artery (PICA)

The posterior inferior cerebellar artery is the largest branch of the vertebral a., and branches off the vertebral a. before the left and right vertebral aa. join to form the basilar a.  The PICA is one of the 3 main arterial supplies to the cerebellum, the other two being the anterior inferior cerebellar a. (AICA), and the superior cerebellar a.  

Left lateral view of the brainstem and cerebellum to show the cerebellar blood supply.