Other Radiological Investigations

Abstract

The vertebral artery arises from the first part of the subclavian artery. It ascends through the foramina in the transverse processes of all cervical vertebrae save the seventh, and begins the V4 and V5 segments. When it leaves the axis, the vertebral artery runs toward the transverse foramen of the atlas while describing a first vertical curve with inward concavity. It issues from this foramen and curves backward behind the lateral mass of the atlas, the second curve being horizontal and anteriorly con-cave. Then, it pierces the dura and enters the skull through the foramen magnum. The two vertebral arteries may be of unequal caliber, and if so, the left vertebral artery is wider than the right. Normal variations in the course are described, as well as abnormal courses in congenital malformations of the cervico-occipital region.