subclavius /səbklā″vē·əs/ [L, sub + clavicula] , a short muscle of the chest wall. It is a small cylindric muscle between the clavicle and the first rib and arises in a short thick tendon from the junction of the first rib and its cartilage under the clavicle. It inserts into the groove on the inferior surface of the clavicle between the costoclavicular and conoid ligaments. The subclavius is innervated by a special nerve from the lateral trunk of the brachial plexus, which contains fibers from the fifth and sixth cervical nerves. It acts to draw the shoulder down and forward. Compare pectoralis major, pectoralis minor, serratus anterior.
