Anatomy of the Upper Limb: Bones of the Shoulder, Arm, Forearm, and Hand

Bones of the Upper Limb

Shoulder Girdle

Clavicle

The clavicle, a long, S-shaped bone, is situated horizontally between the sternum and the scapula. It possesses two curvatures, two surfaces, and two ends.

Scapula

The scapula, or shoulder blade, is a flat, triangular bone located on the posterior aspect of the upper chest. It articulates with the clavicle (acromioclavicular joint) and the humerus (glenohumeral joint).

Arm (Humerus)

The humerus is a long bone with the following features:

• Body: Elongated, almost straight, irregularly cylindrical at the top and triangular prismatic in the lower half. It has three surfaces (internal, external, and posterior) and three edges.
• Upper Extremity: Rounded and smooth articular surface, the head of the humerus, which articulates with the glenoid cavity of the scapula.
• Lower Extremity: Flattened from front to back, featuring the trochlea (articulating with the ulna) and the capitulum (articulating with the radius).

Forearm

The forearm consists of two parallel bones:

Ulna

The ulna, located on the medial side of the forearm, is slightly curved forward at its upper end. Its upper extremity is bulkier and features the olecranon process, forming the prominence of the elbow.

Radius

The radius, located on the lateral side of the forearm, is shorter and less bulky than the ulna. Its upper end articulates with the capitulum of the humerus and the ulna. The lower end articulates with the ulna and the carpal bones (scaphoid and lunate) of the wrist.

Hand

The hand comprises carpal bones, metacarpal bones, and phalanges.