Vertebral artery: course through the transverse foramina to the basilar artery

Where does the vertebral artery run?

The internal carotid in the front of the neck is not the only artery to the brain. A second route runs inside the neck bones themselves: the vertebral artery.

It is the first branch of the subclavian artery at the root of the neck. In the view above both vertebral arteries are yellow, rising straight up along the cervical vertebrae into the skull. They often differ in size, more often larger on the left, but this varies.

Through the transverse foramina

Each cervical transverse process has a transverse foramen. The artery usually enters at C6 and climbs through each foramen in turn, protected by a bony tunnel as the neck moves. After leaving the foramen of the atlas, it turns sharply, runs horizontally in a groove on the posterior arch, pierces the posterior atlanto-occipital membrane and enters the skull through the foramen magnum. Some arteries enter at C5 or C7, and the four-segment classification of its course varies between textbooks.

Forming the basilar artery

Inside the skull the two arteries rise in front of the medulla and unite near the lower border of the pons to form the single basilar artery, an unusual arrangement of two arteries merging into one. This system supplies the brainstem, cerebellum and back of the cerebrum, sends small branches to the spinal cord, and connects with the internal carotid system in the cerebral arterial circle.

Name and terms

Vertebral means of a vertebra. Related terms: transverse foramen, basilar artery, foramen magnum. The Latin is arteria vertebralis.

See it in the app

Running inside bone, the vertebral artery is almost hidden in skeletal drawings. In the 3D anatomy app teamLabBody you can make the bones translucent, select the artery and rotate to follow it up through the transverse foramina and around the atlas. Left and right can be selected separately to compare their size. Cross sections are available with the PREMIUM plan.

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