collarbone

The clavicle, or collarbone, is a slender, S-shaped long bone located horizontally across the upper chest. It connects the sternum to the scapula and serves as the first link in the shoulder girdle. The clavicle helps hold the shoulder blade away from the thorax, enabling a wide range of shoulder movements and acting as a strut that transmits forces from the arm to the axial skeleton.

Each clavicle has a medial (sternal) end that articulates with the manubrium at the sternoclavicular joint and a lateral (acromial) end that articulates with the acromion of the scapula at the acromioclavicular joint. The bone runs just beneath the skin along the superior chest wall.

The clavicle has two natural bends, giving it a double curve. The inferior surface bears landmarks such as the conoid tubercle and the trapezoid line, where the coracoclavicular ligaments attach. Several muscles attach to the clavicle, including the sternocleidomastoid, trapezius, deltoid, and pectoralis major.

Functionally, the clavicle acts as a strut to stabilize and position the shoulder, transmits mechanical forces from the arm to the axial skeleton, and helps protect the underlying neurovascular structures. It also contributes to the wide range of motion of the upper limb.

Developmentally, the clavicle ossifies mainly by intramembranous ossification with a secondary ossification center at the medial end, which fuses in late adolescence to early adulthood. Clinically, clavicle fractures are common, particularly at the midshaft, often resulting from falls or sports. Fractures may risk injury to the subclavian vessels or the apex of the lung, and most are managed nonoperatively, with surgery reserved for severely displaced or open injuries.