The first branch of the subclavian artery, the paired vertebral arteries course superiorly to merge within the cranium as the basilar artery where they contribute to the posterior cerebral circulation.
Arises from posterosuperior aspect of 1st part of subclavian artery, and ascends pyramidal space between longus colli and anterior scalene, posterior to internal carotid artery.
Enters foramen in transverse process of C6 and ascends through foramina C6-C1
Passes out of C1 posteriorly, turning medially over the posterior arch of C1.
Pierces dura and subarachnoid to enter the cranium via the foramen magnum then courses supero-medially anterior to the medulla (passing anterior to the roots of Hypoglossal nerve (CN XII)).
Joins with the vertebral artery from the opposite side at the lower border of the pons to form the basilar artery.
Posterior inferior cerebellar artery
Posterior spinal (occasionally arises from PICA)
Cervical spinal cord
Posterior cerebral circulation
Gives off vertebral & muscular branches in the neck
Vertebral artery dissection; arises from tear in intimal layer of artery. Rarely spontaneous, more often due to trauma. Less common than carotid artery dissection. Expanding haematoma forms between intima and media, resulting in stenosis of vertebral artery. This can lead to posterior circulation infarct.
The vertebral artery follows a relatively straightforward course superiorly through the neck to supply spinal cord, cranial meninges and posterior cerebrum and cerebellum. It is vulnerable to injury which can lead to symptoms of a cerebrovascular accident / transient ischaemic attack.