The vertebral artery is an elaborate network of arteries found in the back of the neck. It originates from the two main blood vessels of the upper chest called the subclavian arteries, joining other arteries such as the internal thoracic artery and dorsal scapular artery as a branch. It is a part of the single mid-line basilar artery that supplies oxygen-rich blood to the brain via the circle of Willis. Thus, it is a major artery of the vertebrobasilar arterial system, which provides blood to significant sections of the brain that include the cerebellum, medulla, mid-brain, occipital cortex, pons and thalamus. The vertebral artery is usually split into four parts.
The first part of the vertebral artery, also known as the prevertebral part, travels in an up-and-down fashion between two muscles of the neck called the Longus colli muscle and anterior scalene muscle. Both are situated at the anterior or front surface of the vertebral column, specifically, at the third to sixth cervical vertebrae. The internal jugular veins, which collect blood from the brain, neck and face, can be found at the prevertebral part. Nerve fibers and tissue masses such as the sympathetic trunk and inferior cervical ganglion, respectively, can be found at the rear.
The second part or atlantal part of the vertebral artery travels upward through the sixth to the second cervical vertebrae. Surrounding it is a complex of tissues and veins that combine to present a vertebral vein. This specialized blood vessel can be found at the upper part of the neck’s back.
The third part of the vertebral artery is called the transverse part. This is because its main site is the foramen transversarium, which is an opening of the seventh cervical vertebrae. Covering the transverse part of the vertebral artery is the Semispinalis capitis, a deep lengthy muscle that helps in extending and rotating the head.
The fourth part of the vertebral artery is referred to as the intracranial part. At its sides are a pair of nerves, the first cranial nerve and the hypoglossal nerve, a cranial nerve that provides motor fibers to virtually all of the tongue’s muscles. The intracranial part of the vertebral artery is notable for being particularly close to the brain, as it goes through this organ’s dura mater membrane and to the front of its lower brain stem, called the medulla oblongata. Part of it can also be found at the pons, which is a section of the brain stem above the medulla oblongata. It is there that it helps form the basilar artery.