V3 Segment of the Vertebral Artery

Anatomical Course and Boundaries

The V3 segment of the vertebral artery extends laterally from the C2 transverse foramen, courses cephalad and posterior to the superior articular process of C2, then travels cephalad and medially across the posterior arch of C1, and continues into the foramen magnum before piercing the dura, as described by the American Heart Association 1, 2, 3

The V3 segment is uniquely connected to highly mobile cervical vertebrae (C1 and C2), making it mechanically vulnerable to injury from sudden or excessive neck movement, according to the American Stroke Association 4

The V3 segment gives off important collateral branches that typically anastomose with branches of the occipital artery at the levels of the first and second cervical vertebrae, as reported by the American Heart Association 1, 2, 3

The V3 segment is particularly vulnerable to dissection and injury due to its mechanical relationship with mobile cervical vertebrae, with an incidence of approximately 1.3 per 100,000 in patients under 45 years within one week of manipulative therapy, according to the American Stroke Association 4
Patients with compromised V3 segment may present with headache and neck pain, vertigo, nausea, and visual disturbances, as described by the American Stroke Association 4
The American Stroke Association recommends considering vertebral artery dissection in patients presenting with Horner syndrome (ptosis, miosis, anhidrosis) after cervical manipulation 4

For patients with suspected V3 segment pathology, CTA or MRA is superior to ultrasound imaging, particularly for dissections beginning cephalad to the angle of the mandible, as recommended by the American Stroke Association 4

Circulation, 2011

Stroke, 2011