QS Study

The vertebral artery is one of the two principal arteries which supply the brain. It branches from the subclavian artery, where it arises from the posterosuperior portion of the subclavian artery.

Origin: It arises from the posterosuperior aspect of the first part of the subclavian artery near its commencement.

Course: ascends posterior to the internal carotid artery in the transverse foramina of the cervical vertebrae.

It is divided into four parts –

1st Part: It extends from the origin of the artery to the transverse process of the sixth cervical vertebra. This part of the artery runs upwards and backward in between scalenus anterior and the longus coli muscles.

2nd Part: It runs through the foramen transversarium of the upper six cervical vertebra. It then runs upwards and laterally to reach the foramen transversarium of the atlas.

3rd Part: Emerging from the foramen transversarium of the atlas, the artery winds medially around the posterior aspect of the atlas. It enters the vertebral canal by passing deep to the lower arched margin of the posterior atlanto-occipital membrane.

4th Part: It extends from the posterior atlantooccipital membrane to the lower border of the pons.

Vertebral Artery 1

Fig: Vertebral Artery Course

Termination: At the lower border of the pons it unites with its fellow of the opposite side to form the basilar artery.

Branches and areas Supply

(A) Cervical branches:

  1. Spinal branches – Spinal cord, meninges, vertebrae.
  2. Muscular branches – Suboccipital muscles.

(B) Cranial branches:

  1. Meningeal branches – Bones and meninges of posterior cranial fossa.
  2. Posterior spinal artery – Posterior one-third of the spinal cord.
  3. Anterior spinal artery – Anterior two-thirds of the spinal cord, part of the medulla.
  4. Posterior inferior cerebellar artery – Posterolateral aspect of the medulla, part of the pons, the cerebellum.
  5. Medullary artery – Medulla.
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