clavicule

The clavicle, or collarbone, is a long, slender, S-shaped bone that runs horizontally across the upper chest, connecting the sternum to the scapula. It acts as a strut that keeps the shoulder blade away from the thorax, helps transmit mechanical loads from the upper limb to the axial skeleton, and protects underlying neurovascular structures.

The bone has a medial (sternal) end that articulates with the manubrium of the sternum at the sternoclavicular joint, and a lateral (acromial) end that articulates with the acromion of the scapula at the acromioclavicular joint. The shaft shows two curvatures and bears important landmarks on its inferior surface: the conoid tubercle near the lateral end for the conoid ligament, and the trapezoid line for the trapezoid ligament. The subclavian groove and the groove for the subclavius muscle run along its inferior border. The clavicle lies over the top of the first rib, with the subclavian vessels and brachial plexus passing posterior to it.

Developmentally, the clavicle forms largely by intramembranous ossification, with a primary ossification center in the midshaft and usually one or more secondary centers at the ends; fusion occurs by late adolescence.

Clinical relevance includes its status as a common fracture site, especially in the middle third. Fractures can affect shoulder function and may risk injury to nearby vessels or nerves. Variations in size, shape, and the relative alignment of the sternoclavicular and acromioclavicular joints may influence mechanics and susceptibility to injury.