The posterior inferior cerebellar artery (PICA, Latin: arteria cerebelli inferior posterior) is the largest branch of the vertebral artery. The PICA is one of the main arteries that supply the cerebellum.
The PICA originates near the inferior end of the olive, then it passes upwards to reach the inferior border of the pons and descends along the lateral border of the fourth ventricle. The artery reaches the undersurface of the cerebellum and divides into two branches, the medial and lateral branches.
The medial branch of the posterior inferior cerebellar artery supplies the medial part of the cerebellar hemisphere and the inferior vermis, while the lateral branch supplies the inferior cerebellar surface and anastomoses with the anterior inferior and superior cerebellar arteries.
The trunk of the posterior inferior cerebellar artery distributes branches to supply the medulla oblongata and its emerging nerve roots, the choroid plexus of the fourth ventricle, and the dentate nucleus.
A severe occlusion of the posterior inferior cerebellar artery (PICA) can lead to the lateral medullary syndrome also known as the Wallenberg syndrome. It causes sensory, muscular dysfunction in the trunk and extremities on the opposite side of the occluded artery.