vertebral artery

Anatomy: Each vertebral artery is the first branch of the subclavian artery. It travels through the transverse foramina of cervical vertebrae C6 to C1, curves around the atlas, and pierces the dura and posterior atlanto-occipital membrane to enter the foramen magnum. Bilateral vertebral arteries unite at the pontomedullary junction to form the basilar artery, which further branches into the posterior cerebral arteries as part of the Circle of Willis.

Branches include the posterior inferior cerebellar artery (PICA), anterior spinal artery, and posterior spinal arteries.

Clinical significance: Vertebral artery dissection is an important cause of stroke in young patients, often following trauma or neck manipulation (e.g., chiropractic adjustment), and can present with neck pain, headache, and posterior circulation stroke symptoms. Occlusion of the vertebral artery or PICA causes lateral medullary (Wallenberg) syndrome, characterized by dysphagia, hoarseness, ipsilateral facial pain/temperature loss, ipsilateral Horner syndrome, ipsilateral limb ataxia, and contralateral body pain/temperature loss.

Vertebrobasilar insufficiency can cause symptoms of dizziness, vertigo, diplopia, dysarthria, and drop attacks, particularly with neck rotation (compressing the artery, especially at C1-C2). Subclavian steal syndrome occurs when subclavian artery stenosis proximal to the vertebral artery origin causes retrograde flow in the vertebral artery, stealing blood from the posterior circulation during arm exercise, leading to syncope or vertigo.

Understanding vertebral artery anatomy is critical for interpreting posterior circulation strokes and for procedures involving the cervical spine.