The posterior inferior cerebellar artery (or PICA) is an artery that provides blood flow to the cerebellum, a part of the brain located behind the top of the brain stem, which helps with functions related to movement and coordination. Out of all the cerebral arteries, the posterior inferior cerebellar artery is considered the most variable. It is mostly made up of the supratonsillar segment and parts of the medulla.

The posterior inferior cerebellar artery generally supplies blood to the inferior (lower) portion of the vermis (the midline segment of the cerebellum), the lower medulla, and the posteroinferior cerebellar hemispheres.

Occlusion, or blockage, of the posterior inferior cerebellar artery may cause an infarction (loss of blood supply) of the medulla oblongata, which plays an important role in circulatory and respiratory functioning. This may lead to lateral medullary syndrome, also called Wallenberg syndrome, which may then result in tissue necrosis (death of cells in the tissue). One major symptom of this syndrome is diminished sensations of pain and extreme temperature below the chin, and on portions of the face. Other symptoms include vertigo, hiccups, nausea, dysphagia, and gait (walking) imbalance. Speech or swallowing therapy is sometimes used to treat this syndrome. In severe cases, a person with Wallenberg syndrome might need a feeding tube to compensate for swallowing malfunction. Blood thinners, such as warfarin or heparin, may also be used.