What are the primary bones that compose the shoulder?

The shoulder is primarily composed of the clavicle and scapula, which together form the shoulder girdle. The clavicle, commonly known as the collarbone, connects the arm to the body and helps stabilize the shoulder by acting as a strut. It articulates with the scapula at the acromioclavicular joint and the sternum at the sternoclavicular joint.

The scapula, or shoulder blade, provides a surface for muscle attachment and allows for a wide range of motion in the shoulder joint. It is a flat, triangular bone located on the posterior side of the thorax. The humerus, which is the long bone in the upper arm, connects to the scapula at the glenohumeral joint, which is the ball-and-socket joint of the shoulder.

Options that include the radius or femur are unrelated to the anatomy of the shoulder. The radius is one of the bones in the forearm, while the femur is the thigh bone. The frontal and nasal bones pertain to the skull and facial structure, respectively, and have no connection to shoulder anatomy. This understanding emphasizes the significance of the clavicle and scapula in providing both structural support and mobility to the shoulder joint.