kragebein

Kragebein, known in English as the clavicle, is a long, slender bone that forms part of the shoulder girdle. It extends horizontally from the manubrium of the sternum medially to the acromion of the scapula laterally, linking the upper limb to the axial skeleton.

In adults the clavicle measures about 15 cm in length and has a characteristic S-shaped curvature, with the medial end (sternal end) convex anteriorly and the lateral end (acromial end) concave. The medial end articulates with the manubrium at the sternoclavicular joint, while the lateral end articulates with the acromion at the acromioclavicular joint. The bone lies just beneath the skin over the first rib, providing some protection to deeper structures and serving as a transmission point for forces from the upper limb.

The clavicle serves several important functions. It acts as a strut that holds the scapula away from the thorax, enabling a wide range of shoulder movements. It transmits mechanical load from the upper limb to the axial skeleton and provides attachment sites for multiple muscles, including pectoralis major, deltoid, trapezius, sternocleidomastoid, and subclavius. The clavicle also helps cushion movements of the shoulder and protects underlying neurovascular structures to a degree.

Development and clinical notes: The clavicle develops largely by intramembranous ossification, with secondary ossification centers appearing at the ends during adolescence. Clinically, clavicular fractures are common, particularly in the middle third, due to its subcutaneous location and exposure to trauma. Fractures typically present with pain, swelling, and possible deformity; treatment ranges from immobilization with a sling to surgical fixation in displaced or complicated cases.