The Scapula and Clavicle

THE SCAPULA AND CLAVICLE

The scapula, or shoulder blade, is located overlying the upper back. It is supported by the

clavicle, which is located in the upper anterior chest. These two bones are connected and form

the pectoral girdle, which connects the upper limbs to the body.

The clavicle is considered a long bone and serves to anchor several muscles that support the

scapula. It holds the shoulder joint in position, while allowing for the maximal amount of

freedom of motion of the joint. Its function also includes protecting crucial underlying vessels

and nerves as they pass between the trunk of the body and the upper limb. There are two joints

that are part of the clavicle: the medial sternoclavicular joint and the lateral acromioclavicular

joint.

The clavicle is the most commonly broken bone in the body. It occurs when a person falls into

an outstretched arm or when there is a lateral blow to the shoulder. The sternoclavicular joint

is very strong so, after an injury, the bone breaks rather than dislocating the joint. The

segments of broken bone also tend to overlap because of the weight of the arm and shoulder

acting on the bony fragments.

The scapula anchors the upper limb to the body and is located on the back of the shoulder. It is

surrounded by multiple muscles and articulates with the humerus and the clavicle. The bone is

triangular with a superior, medial, and lateral border. The three corners of the triangle are the superior angle (medially-located), the inferior angle, and the glenoid cavity/glenoid fossa (that

articulates with the humerus). It has two large projections, the coracoid process and the

acromial process. The coracoid process is anchored to the clavicle by a strong ligament. The

acromial process forms the acromioclavicular joint. Figure 43 illustrates the scapula and its

projections: