The subclavian artery is a large, paired blood vessel lying in the shoulder region. It supplies the brain, neck, shoulder, chest, and the upper limb with oxygenated blood, giving off important arterial branches; some of them have long and irregular courses. To make an anatomical description easier, the subclavian is usually divided into three parts: the first part stretches from the site of origin of the vessel to the medial border of the anterior scalene muscle; the second portion extends behind this muscle; while the third section runs through the lateral margin of the muscle to outer border of first rib.
Origin of the blood vessel
The right subclavian artery arises from the brachiocephalic trunk (also known as innominate artery), behind the upper portion of the right sternoclavicular articulation, while the left subclavian originates directly from the arch of aorta. As a result, the left is longer than the right. Then both of them runs upwards and laterally, making a curve, to the inlet of the thorax and arches across the dome of the pleura and the apex of the lung on which it leaves a small depression, which is called the groove for the subclavian artery.
Branches
The first portion of the subclavian artery gives off three important branches: 1) the vertebral artery, which arises from the upper side of subclavian and travels upwards through the transverse process of cervical vertebrae, entering the cranium through the foramen magnum to supply a large portion of the brain; 2) the internal thoracic artery, which originates from the lower surface of the subclavian, descending almost vertically behind the ribs and close and parallel to the sternum, dividing into two terminal offshoots (the musculophrenic and the superior epigastric artery); 3) the thyrocervical trunk, which divides into four branches that supply the muscles of neck and shoulder as well as the thyroid gland (inferior thyroid, ascending cervical, suprascapular, and transverse cervical artery).
The second part of subclavian artery gives off only one branch, which is the costocervical trunk. This arterial trunk forks, in turn, into two branches: the deep cervical and the superior intercostal artery, supplying the posterior deep muscles of neck and spinal cord as well as muscles of the back respectively.
The third portion of subclavian artery also gives off only one branch: the dorsal scapular artery, which is an inconstant arterial offshoot. Sometimes it arises as a long branch of the transverse cervical or suprascapular artery of thyrocervical trunk.
