The neck is responsible for supplying and draining cervical structures, as well as those in the head. The vessels that make up the neck are the largest arteries, including the common carotids, the vertebral arteries, the thyrocervical trunks, and the jugular veins. Each of these vessels contributes to the blood supply of the head and neck and can be divided into superficial and internal branches.
The common carotids, the largest arteries of the neck, arise from the brachiocephalic trunk on the right side and a direct branch from the arch of the aorta on the left side. They ascend in the neck and bifurcate at the level of C4, giving rise to the external and internal carotids. The external carotids are superficial arteries and supply the head and neck external to the cranium. They form eight main branches bilaterally, all of which are distributed to the muscular structures of the neck. The internal carotids ascend in the neck and enter the cranium via the carotid canals, providing the major blood supply for the eyes, brain, and forehead.
The vertebral arteries are additional contributors to the intracranial blood supply. They arise from the subclavian arteries and course through the transverse foramina of the cervical vertebrae before entering the cranium via the foramen magnum. The vertebral arteries provide circulation to the brain stem, cerebellum, and spinal cord.
The thyrocervical trunks arise from the subclavian arteries and branch to supply blood to the thyroid and various muscles in the neck. The thyrocervical trunks are responsible for supplying nutrition to the muscular and endocrine structures of the neck and upper thorax, as well as providing a courier for metabolic waste from the region.
The jugular veins are the major veins of the neck. The internal jugular vein is a continuation of the sigmoid sinus and courses inferiorly within the carotid sheath. It collects tributaries in the neck and merges with the subclavian vein in the base of the neck to form the brachiocephalic vein. The external jugular vein drains the external face and descends from the angle of the mandible within the superficial fascia. It crosses sternocleidomastoid and drains into the subclavian vein, as do the anterior jugular veins. The anterior jugular veins, however, show anatomical variability and drain the anterior neck, usually descending together near the midline of this territory.
Also associated with the vessels of the neck is the lymphatic system. Lymph from superficial parts of the head and neck join with that from deeper structures after passing through superficial lymph nodes, which form a ring. All of the lymph is collected in the jugular lymphatic trunks before draining into the subclavian veins. One of the major lymphatic components of the neck is Waldeyer's ring, an array of lymphatic tissue encircling the superior pharynx serving to defend against inhaled or ingested pathogens.
