Checks inferior glide, lateral displacement and depression of clavicle. Depression is also checked by bony contact of lateral clavicle with the 1st rib. The axis is the costoclavicular ligament. All of clavicular elevation occurs by 150 o of elevation . Therefore, the medial end of the clavicle moves in the opposite direction to the lateral clavicle.
Protraction is anterior movement of the lateral end of the clavicle.
For this movement-the medial end of the clavicle is concave and the manubrium is convex. The medial clavicle moves in the same direction as the lateral clavicle. As the scapula protracts, the clavicle protracts. Protraction is checked by the costoclavicular ligament and the anterior SC ligament. Retraction is checked by the costoclavicular and posterior SC ligament.