Arteries of the Head and Neck

The paired common carotid arteries supply the head and neck and three paired branches of the right and left subclavian arteries: the vertebral arteries, thyrocervical trunks, and costocervical trunks.

Common Carotid Arteries Branches of the common carotid arteries supply blood to the head and brain. The right common carotid originates from the brachiocephalic trunk. The left common carotid is the second branch of the aortic arch. At the "Adam's apple," the common carotids divide into the external and internal carotid arteries.

The external carotid artery supplies most external head structures, except the orbits. It gives rise to thesuperior thyroid artery, which supplies the thyroid gland and larynx; the lingual artery, which supplies the tongue; the facial artery, which supplies the skin and muscles of face; the occipital artery, which supplies the posterior scalp; the maxillary artery, which supplies the teeth, maxilla, buccal cavity, external ear; and the superficial temporal artery, which supplies the chewing muscles, nasal cavity, lateral aspect of face, most of the scalp, and the dura mater around brain. A branch of the maxillary artery, the middle meningeal artery, supplies the dura mater and cranial cavity. Injury to the head that ruptures the middle meningeal artery causes epidural hematoma, which can be fatal. The internal carotid artery supplies the orbits and more than 80 percent of the cerebrum. It gives rise to the ophthalmic artery, which supplies the orbits, nose, and forehead; the anterior cerebral artery, which supplies the medial aspect of the cerebral hemisphere, and the middle cerebral artery, which supplies the lateral aspect of temporal and parietal lobes. The internal carotid arteries have a carotid sinus with baroreceptors that help regulate BP. Pressure on the neck near the carotid sinuses can cause unconsciousness, because it simulates high blood pressure, eliciting a reflex vasodilation and interfering with blood flow to the brain.

Vertebral Arteries Branches of the vertebral arteries supply blood to the neck structures and the spinal cord. They originate from the subclavian arteries at the base of the neck and unite in the brain stem to form the basilar artery. The basilar artery branches supply the cerebellum, pons, and inner ear. At the junction of the pons and midbrain, the basilar artery flows into the arterial circle where it divides into two posterior cerebral arteries that supply the occipital lobes and inferior portions of temporal lobes.

The thyrocervical trunks supply the thyroid gland and some scapular muscles. They are small vessels that originate from the subclavian arteries. Costocervical trunks arise from the subclavian arteries and supply blood to the deep neck muscles and some intercostal muscles of superior rib cage.

Arterial Circle The arterial circle, also called the circle of Willis, is an arrangement of arteries surrounding the pituitary gland and optic chiasm. It creates redundancies to ensure blood supply to the brain if one artery feeding the circle—or a part of the circle—is damaged. The arterial circle is fed anteriorly by the left and right carotid arteries and posteriorly by the basilar artery. The circle itself is composed of two posterior communicating arteries, and one anterior communicating artery. Branches off of the circle include two posterior cerebral arteries, two middle cerebral arteries, and two anterior cerebral arteries.

Arteries of the Thorax The wall of the thorax is supplied by a collection of arteries, some of which originate directly from the thoracic aorta and others from branches of the subclavian artery. Two bronchial arteries on the left and one on the right deliver systemic blood to the lung structures, including the visceral pleura, esophagus, and bronchi of lungs. Blood is also delivered to the esophagus by the four or five esophageal arteries. Numerous small mediastinal arteries deliver blood to the posterior mediastinal structures.

Nine pairs of posterior intercostal arteries wrap around the rib cage before anastomosing anteriorly with the anterior intercostal arteries. The first pair arises from the costocervical trunk and the rest from the thoracic aorta. They supply blood to the skin and subcutaneous tissue, breasts, spinal cord and meninges, and pectoralis, intercostal, and some abdominal muscles. The distribution of the subcostal arteries is similar to that of the posterior intercostal arteries. They supply blood to the posterior intercostal tissues, vertebrae, spinal cord, and deep muscles of the back. One or more pairs of the small superior phrenic arteries supply blood to the posterosuperior surface of diaphragm.

Internal thoracic arteries, also called the mammary arteries, originate from the subclavian artery and supply the breast tissue. Their branches, the anterior intercostal arteries, supply the intercostal spaces anteriorly.