The vertebral artery is a major artery of the neck that passes through the cervical vertebrae. There are two vertebral arteries, one on each side, and each branches off from the subclavian artery. They merge to form the single basilar artery at the base of the brain.
The vertebral artery originates from the subclavian artery and runs upward and backward between the longus colli and the anterior scalene muscles before passing through the holes of the upper six cervical vertebrae. It then reverses direction, curving backward behind the superior articular process of the atlas then coming to lie in the groove on the upper surface of the posterior arch of the atlas. It then enters the vertebral canal by passing underneath the posterior atlanto-occipital membrane and pierces the dura mater to enter the cranium. It can vary in diameter from 0.02 to 0.22 inches and in length from 2 to 14 inches. The branches of the vertebral artery can be categorized in two types: those that branch off in the neck and those that branch off within the cranium.
Within the neck, the lower part of the vertebral artery branches off to the sides into spinal branches, which enter the vertebral canal to connect with the other arteries of the spinal cord and form chains of arteries on the inside of the vertebrae. The upper part branches into muscular branches that originate where the vertebral artery curves around the atlas and connect with the occipital, ascending and deep cervical arteries.
There are five branches of the vertebral artery within the cranium: meningeal, posterior spinal, anterior spinal, posterior inferior cerebellar and medullary.
The meningeal branch originates opposite the foramen magnum and supplies the falx cerebelli.
The posterior and anterior spinal arteries originate, respectively, at the side of the medulla oblongata and near the end of the vertebral artery. From there, they both turn backward, entering the vertebral canal and traveling down the spinal cord to reach the cauda equina.
The posterior inferior cerebellar artery is the largest branch of the vertebral artery. It winds backward around the upper part of the medulla oblongata and reaches the underside of the cerebellum, where it further divides in two branches, both supplying various areas of the cerebellum.
The medullary arteries are small vessels that can originate from the vertebral artery as well as any of its other branches; they supply the medulla oblongata.
Vertebral Artery Dissection
Damage to the vertebral artery is an increasingly recognized cause of stroke in young people. This pathology, called vertebral artery dissection, originates from a small tear in the wall of the artery; this leads to the formation of a thrombus (blood clot) on the inside of the artery, restricting blood flow to the brain. Parts of the thrombus may also break off, causing an embolism. The dissection usually happens in the upper part of the artery, where it loops around the atlas.
Past medical studies identified chiropractic manipulation of the neck as the cause of strokes. The studies asserted that manipulation of the spinal column in the neck area led to vertebral artery dissection, based on the fact that some patients suffered a stroke caused by vertebral artery dissection some time after receiving chiropractic therapy. Recent evidence, however, has clarified the relationship considerably, suggesting that patients suffering from undiagnosed vertebral artery dissection display symptoms that cause them to seek out a chiropractor for relief.
- "Anatomy of the Human Body"; Henry Gray; 1918
- "Advances in Neurology", Vol. 30; Vertebral Artery Surgery: Historical Development, Basic Concepts of Brain Hemodynamics, and Clinical Experience of 102 Cases; Andrew L. Carney; 1981
- Dissection, Vertebral Artery; Eddy Lang, Mark Afilalo
- Current understanding of the relationship between cervical manipulation and stroke: what does it mean for the chiropractic profession?; Donald R. Murphy
- EurekAlert: Chiropractic treatment of the neck can be a risk factor for stroke
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