Surgical Anatomy of Carotid and Vertebral Arteries
Arterial supply to the brain is from the internal carotid arteries and from the vertebral arteries coursing on either side of the neck. These arteries arise as branches of the brachiocephalic trunk, left common carotid, and left subclavian arteries. The latter are also called supra-aortic trunks and arise from the arch of the aorta. The brachiocephalic trunk divides into the right subclavian artery and the right common carotid artery (CCA). Each CCA divides near the angle of the jaw into the external and internal carotid arteries. The internal carotid artery divides into the anterior and middle cerebral artery which supplies anterior two-thirds of the brain.
Both vertebral arteries arise from the first portion of the subclavian artery and ascend to enter the transverse foramina of the cervical vertebrae and then enter the skull and join together to form the basilar artery. The terminal branches of the basilar artery are two posterior cerebral arteries supplying posterior one-third of the brain. The common carotid artery and internal carotid artery with the internal jugular vein are contained within the carotid sheath which also includes the vagus nerve. Other important nerves in the neck are hypoglossal, ansa cervicalis, superior laryngeal, glossopharyngeal, and spinal accessory nerve.
There are many anatomic variations in the arteries and nerves of the neck. Occasionally there are persistent embryological carotid-basilar connections. These variations have important surgical implications.