Posterior inferior cerebellar artery

At a glance

English

Posterior inferior cerebellar artery

Latin (TA2)

Arteria cerebelli inferior posterior

System

Artery

Region

Head

Side

Paired, left and right

About the posterior inferior cerebellar artery

The posterior inferior cerebellar artery, usually shortened to PICA, is one of three paired arteries that supply the cerebellum, along with the anterior inferior and superior cerebellar arteries. It is the biggest branch of the vertebral artery, normally arising from it beside the medulla oblongata shortly before the two vertebrals unite to form the basilar artery.

From its origin it curves backwards around the upper medulla, passing between the rootlets of the vagus and accessory nerves, and often between those of the glossopharyngeal nerve as well. It then climbs over the inferior cerebellar peduncle, frequently forming a loop near the lower part of the fourth ventricle, and reaches the inferior surface of the cerebellum. There it divides into two terminal branches. The medial branch runs back into the notch between the cerebellar hemispheres and supplies the vermis and nearby hemisphere. The lateral branch spreads over the under surface of the hemisphere to its lateral border, where it joins branches of the anterior inferior and superior cerebellar arteries.

Along its way it gives perforating branches to the lateral and posterior medulla and a branch to the fourth ventricle's choroid plexus. Its size and origin vary; it may arise from below the foramen magnum, share a trunk with the anterior inferior cerebellar artery or be absent, in which case neighbouring arteries take over.

Blockage of the PICA, or of the vertebral artery from which it comes, by a clot or embolus causes the lateral medullary, or Wallenberg, syndrome. Typical features include vertigo, unsteadiness, difficulty swallowing and hoarseness, loss of pain and temperature on the same side of the face and the opposite side of the body, and Horner's syndrome on the side of the lesion. Infarction of the cerebellar territory may also cause swelling that compresses the brainstem.

Course and supply

Arises from

The vertebral artery, alongside the medulla oblongata.

Ends in

Divides on the inferior surface of the cerebellum into medial and lateral branches that join the other cerebellar arteries.

Supplies

Supplies the lower surface of the cerebellum and inferior vermis, the lateral and posterior medulla, and the fourth ventricle's choroid plexus.