Subclavian artery

In human anatomy, the subclavian arteries are paired major arteries of the upper thorax, below the clavicle. They receive blood from the aortic arch. The left subclavian artery supplies blood to the left arm and the right subclavian artery supplies blood to the right arm, with some branches supplying the head and thorax. On the left side of the body, the subclavian comes directly off the aortic arch, while on the right side it arises from the relatively short brachiocephalic artery when it bifurcates into the subclavian and the right common carotid artery.

The usual branches of the subclavian on both sides of the body are the vertebral artery, the internal thoracic artery, the thyrocervical trunk, the costocervical trunk and the dorsal scapular artery, which may branch off the transverse cervical artery, which is a branch of the thyrocervical trunk. The subclavian becomes the axillary artery at the lateral border of the first rib.

From its origin, the subclavian artery travels laterally, passing between anterior and middle scalene muscles, with the anterior scalene on its anterior side and the middle scalene on its posterior. This is in contrast to the subclavian vein, which travels anterior to the anterior scalene. As the subclavian artery crosses the lateral border of the first rib, it becomes the axillary artery.

On the right side, the subclavian artery arises from the brachiocephalic (innominate) artery behind the right sternoclavicular articulation; on the left side it springs from the arch of the aorta. The two vessels, therefore, in the first part of their course, differ in length, direction, and relation with neighboring structures. The left subclavian artery is around 9 cm long in adults, while the right subclavian artery is around 6 cm long. Both have a width of 9-12 mm.

In order to facilitate the description, each subclavian artery is divided into three parts:

The first portions of the two vessels require separate descriptions; the second and third parts of the two arteries are practically alike.

The first part of the right subclavian artery arises from the brachiocephalic trunk, behind the upper part of the right sternoclavicular articulation. It passes upward and lateralward to the medial margin of the scalenus anterior muscle. It ascends a little above the medial part of the clavicle.

It is covered, in front, by the integument, superficial fascia, the platysma muscle, deep fascia, the clavicular origin of the sternocleidomastoid muscle, the sternohyoid muscle, and the sternothyroid muscle, and another layer of the deep fascia. It is crossed by the internal jugular vein and the vertebral vein, by the vagus nerve and the cardiac branches of the vagus and sympathetic, and by the subclavian loop of the sympathetic trunk which forms a ring around the vessel. The anterior jugular vein is directed laterally in front of the artery, but is separated from it by the sternohyoid muscle and the sternothyroid muscle. Below and behind the artery is the pleura, which separates it from the apex of the lung. Behind the artery is the sympathetic trunk, the longus colli muscle and the first thoracic vertebra (T1). The right recurrent laryngeal nerve winds around the lower and back part of the vessel.