(anatomy) Either of two arteries that occur one on each side of the circle of Willis and connect an internal carotid artery with a posterior cerebral artery.

(anatomy) Any of three arteries in the brain that form parts of the circle of Willis.

(anatomy) An artery that usually branches from the vertebral artery below its junction with the contralateral vertebral artery to form the basilar artery and that supplies much of the medulla oblongata, the inferior portion of the cerebellum, and part of the floor of the fourth ventricle.

(anatomy) Any of several branches of the basilar and vertebral arteries that supply the cerebellum.

(anatomy) An artery that arises from the basilar artery either alone or by a common trunk with the labyrinthine artery, divides into branches distributed to the anterior parts of the inferior surface of the cerebellum, and gives off a branch that anastomoses with the posterior inferior cerebellar artery.

(anatomy) An artery that arises from the basilar artery just before it divides to form the posterior cerebral arteries and supplies or gives off branches supplying the superior part of the cerebellum, midbrain, pineal gland, and choroid plexus of the third ventricle.

(anatomy) An unpaired artery that is formed by the union of the two vertebral arteries, runs forward within the skull just under the pons, divides into the two posterior cerebral arteries, and supplies the pons, cerebellum, posterior part of the cerebrum, and the inner ear.

(anatomy) A large branch of the subclavian artery that ascends through the foramina in the transverse processes of each of the cervical vertebrae except the last one or two, enters the cranium through the foramen magnum, and unites with the corresponding artery of the opposite side to form the basilar artery.

(anatomy) A long slender artery that arises from the basilar artery or one of its branches, accompanies the vestibulocochlear nerve through the internal auditory canal, and is distributed to the inner ear.

(anatomy) Any of the several arteries supplying blood to the meninges of the brain and neighboring structures.