Vertebral artery

At a glance

English

Vertebral artery

Latin (TA2)

Arteria vertebralis

System

Artery

Region

Head

Side

Paired, left and right

About the vertebral artery

The vertebral artery is one of the main sources of blood for the brain. There is one on each side, usually the first branch of the subclavian artery, arising from its upper and back surface. The two arteries rise through the neck inside a bony channel and then enter the skull, where they unite to form the basilar artery. Together they make up the vertebrobasilar, or posterior, circulation that serves the brainstem, cerebellum, back of the cerebrum and upper spinal cord.

Its course is described in four segments. The first runs up and back from the subclavian, in the angle between longus colli and scalenus anterior, behind the common carotid artery and vertebral vein; the inferior thyroid artery crosses in front of it, and on the left so does the thoracic duct. The second segment usually enters the transverse foramen of C6 and climbs vertically through the foramina of C6 to C2, surrounded by a venous plexus and sympathetic fibres, in front of the cervical nerve roots. The third segment leaves C2, passes up through the transverse foramen of the atlas, then curves backwards and medially round its lateral mass to lie in a groove on the posterior arch, within the suboccipital triangle, before passing under the posterior atlanto-occipital membrane. The fourth pierces the dura and arachnoid, runs forwards round the medulla, and where the medulla meets the pons it joins its partner.

Along the way it gives spinal and muscular branches in the neck and meningeal branches near the foramen magnum. Inside the skull it gives the anterior and posterior spinal arteries to the cord and the posterior inferior cerebellar artery, which supplies the lower cerebellum and lateral medulla. The basilar artery it forms joins the arterial circle at the base of the brain.

The two arteries are often unequal, the left usually larger, and one may be very small. A bony bridge over the groove on the atlas occurs in some people. Tearing of the inner wall, known as dissection, can follow neck trauma or sudden neck movements, including manipulation, and may cause a posterior circulation stroke with dizziness, double vision, unsteadiness or difficulty swallowing. Lateral medullary syndrome results from blockage of the posterior inferior cerebellar artery or the vertebral artery itself.

Course and supply

Arises from

Arises from the upper and posterior surface of the first part of the subclavian artery, usually as its first branch.

Ends in

Ends at the pontomedullary junction, where it merges with its partner to create the basilar artery.

Supplies

Supplies the upper spinal cord, the medulla, the cerebellum (through the posterior inferior cerebellar artery) and, via the basilar artery, the pons, midbrain and posterior cerebrum; also deep neck muscles and the meninges of the posterior cranial fossa.