Vertebral artery !

The vertebral artery runs up each side of the neck through holes in C6 to C1, then into the skull; it feeds the back of the brain.

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What it is

An artery on each side of the neck that runs up through holes in the transverse processes of C6 to C1, then into the skull.

What it does

Supplies the back of the brain, the brainstem and the top of the spinal cord.

Key facts

Origin: First part of the subclavian artery; ascends through transverse foramina C6–C1; enters skull via foramen magnum
Branches: Spinal (radicular) and muscular branches in the neck; anterior and posterior spinal; PICA; joins the other to form the basilar artery
Supplies: Cervical cord, deep neck muscles, brainstem, cerebellum, occipital lobes (via basilar)

Relations

Course: Rises from the subclavian artery between the longus colli and scalenus anterior, enters the C6 transverse foramen, climbs through the foramina to the atlas, curves back behind its lateral mass in a groove on the posterior arch, pierces the atlanto-occipital membrane and dura and enters the skull through the foramen magnum
In front: At the root of the neck, the common carotid artery and the vertebral vein in front of its first part, with the inferior thyroid artery arching across it at about C7 (on the left, also the thoracic duct)
Medial: Uncovertebral joints and vertebral bodies; osteophytes from these joints can press on it
Behind: First part: the C7 transverse process, the cervicothoracic (stellate) ganglion and the ventral rami of C7 and C8; higher up, the ventral rami of the cervical spinal nerves, which pass behind it as they leave the foramina
Above: At the atlas it lies in the suboccipital triangle, with the suboccipital nerve between it and the posterior arch

How to find it

It cannot be felt. In posterior exposures it lies in the suboccipital triangle (rectus capitis posterior major and the two obliques) on the posterior arch of the atlas; in anterior surgery it lies just lateral to the uncovertebral joints, which mark the safe lateral limit.

On imaging

CT or MR angiography shows its course and dominance (the left is often larger); axial CT shows whether a fracture enters a transverse foramen.

Common problems

Can be torn (dissection) in neck trauma or, rarely, forceful neck manipulation: a cause of stroke in younger people.
Sets the side limit in anterior neck surgery and the path for screws at C1-C2.

How it is diagnosed

CT or MR angiography.

Treatment

Dissections are usually treated with blood thinners; surgeons study its course on scans before neck surgery.

Clinical notes

In posterior C1 exposure, dissection along the upper border of the posterior arch is usually kept within about 1.5 cm of the midline to avoid the artery
C1–C2 transarticular screws and C2 pedicle or pars screws need its path checked on CT first, as a high-riding artery can make them unsafe
Rotational vertebral artery occlusion (bow hunter's syndrome): turning the head compresses the artery near C1–C2, causing dizziness or fainting

Anatomical variants

The left artery arises directly from the aortic arch in about 1 in 20 people
It enters the C6 foramen in most people (about 9 in 10), otherwise at C5, C4 or C7
A bony bridge over the groove on the atlas (ponticulus posticus) can be mistaken for a wide posterior arch when C1 screws are placed

Development

Its neck part forms from a longitudinal chain linking the upper cervical segmental arteries, and the seventh segmental artery becomes its origin from the subclavian; this explains entry into a foramen other than C6 and origins from the aortic arch.

Test yourself

Think of the answer, then tap the question to see it.

Where does the vertebral artery arise, and at which level does it usually enter the transverse foramina?

From the first part of the subclavian artery; it usually enters the C6 transverse foramen (about 9 in 10 people) and climbs to C1.

What are the four segments of the vertebral artery?

V1 subclavian to C6; V2 in the transverse foramina C6–C2; V3 looping behind the atlas; V4 inside the skull to the basilar artery.

In which triangle does the vertebral artery lie on the posterior arch of the atlas?

The suboccipital triangle, with the suboccipital nerve between the artery and the posterior arch.

What is subclavian steal, and how does it involve the vertebral artery?

A blocked proximal subclavian artery draws reversed flow down the vertebral artery, so arm exercise can cause dizziness.

Which landmark marks the safe lateral limit for the vertebral artery in anterior cervical surgery?

The uncovertebral joints: the vertebral artery lies just lateral to them.

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Educational information, not medical advice. For any symptom, see a health professional.

Its names

Official Latin (TA2): arteria vertebralis TA2 4538
Official Spanish (DeCS): Arteria vertebral DeCS D014711
English (TA2): Vertebral artery

Sources: Terminologia Anatomica (TA2); DeCS; Anatomy, Head and Neck: Cervical Vertebrae; Anatomy, Head and Neck, Occipital Bone, Artery, Vein, and Nerve; Anatomy of the Human Body (20th ed.): Development of the Vascular System (Lea & Febiger (Gray's Anatomy, 1918), 1918) · adapted, Public domain; Tratado de anatomía humana (9.ª ed.), tomo II, Libro IV Angiología, arterias subclavia, axilar, humeral, radial y cubital, arcos palmares y vías anastomóticas del miembro superior.

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Representative model, for educational purposes only.

Vertebral artery highlighted on the Durgical 3D model