On the right side, the subclavian artery originates from the innominate (brachiocephalic) artery, which branches into the right subclavian and right common carotid arteries. On the left side, it originates directly from the aortic arch. In some individuals, the left subclavian artery may have a common origin with the left common carotid artery.

The subclavian artery courses laterally, passing between the anterior and middle scalene muscles. This is in contrast to the subclavian vein, which is located superficial to the anterior scalene muscle.

The subclavian artery is divided into three parts on the basis of its relationship to the anterior scalene muscle. The first part extends from its origin to the medial border of the anterior scalene muscle, coursing deep to the sternocleidomastoid and the strap muscles. It gives rise to the vertebral, internal mammary (internal thoracic), and thyrocervical arteries. The second part lies deep to the anterior scalene muscle and superficial to the upper and middle trunks of the brachial plexus. Here, it gives rise to the costocervical artery (on the left side, costocervical artery comes off the first part of the subclavian artery). The third part is located lateral to the anterior scalene muscle, and courses over the lower trunk of the brachial plexus, usually giving rise to the dorsal scapular artery, although its branches are not constant.

The subclavian artery continues as the axillary artery, as it passes over the first rib. The external landmark for this transition is the lower border of the middle of the clavicle. The external landmark for the axillary artery is a curved line from the middle of the clavicle to the deltopectoral groove.

The subclavian vein is the continuation of the axillary vein and originates at the level of the outer border of the first rib. It crosses in front of the anterior scalene muscle, and at the medial border of the muscle, it joins the internal jugular vein to form the innominate (brachiocephalic) vein. The left thoracic duct drains into the left subclavian vein at its junction with the left internal jugular vein. The right thoracic duct drains into the junction of the right subclavian vein and right internal jugular vein.

The vagus nerve is in close proximity to the first part of the subclavian artery and it lies medial to the internal mammary artery. On the right side, it crosses in front of the artery and immediately gives off the recurrent laryngeal nerve (RLN), which loops behind the subclavian artery and ascends behind the common carotid artery into the tracheoesophageal groove. On the left side, the vagus nerve travels between the common carotid and subclavian arteries and immediately gives rise to the RLN, which loops around the aortic arch and ascends into the tracheoesophageal groove.