Anatomy of the human forearm

The forearm is the area of the upper limb between the elbow and wrist joints. Despite its relatively small size, it contains an astonishing number of anatomical structures: two bones, more than twenty muscles, key nerves and blood vessels.

Bones of the forearm

The skeleton of the forearm is formed by two tubular bones:

• Radius (radius) - located laterally (from the side of the thumb). It expands downwards and forms the main articular surface of the wrist joint.
• Ulna (ulna) - located medially. It has a massive upper end with an olecranon process, which we feel as an “elbow”.

Stretch between the bones is the interosseous membrane - a dense connective tissue septum that not only connects the bones, but also serves as a site for muscle attachment. It is thanks to the movable articulation of the radius and ulna that we can perform pronation (turning the palm down) and supination (turning the palm up).

Muscles: anterior and posterior groups

The muscles of the forearm are divided into two groups:

Anterior group (flexors) - located on the palmar surface. Includes superficial and deep layers. The superficial flexors originate from the medial epicondyle of the humerus and are responsible for flexing the hand and fingers. Deep - for subtle movements of the fingers.

Posterior group (extensors) - located on the dorsal surface. Starts from the lateral epicondyle. Provides extension of the hand and fingers, as well as abduction and adduction of the hand.

Nerves and blood vessels

Three main nerves pass through the forearm:

• Median nerve - innervates most of the flexors and the skin of the palmar surface of the I–III fingers
• Ulnar nerve - responsible for fine motor skills of the hand and sensitivity of the IV–V fingers
• Radial nerve - innervates the extensors

Blood supply is provided by the radial and ulnar arteries - branches of the brachial artery. It is at the radial artery (at the base of the thumb) that we traditionally measure the pulse.

Frequent injuries

A fracture of the radius “in a typical location” (Colles fracture) is one of the most common injuries in orthopedics. It occurs when falling onto an outstretched arm and affects the distal metaepiphysis of the radius. Knowledge of the anatomy of the forearm helps the surgeon accurately align the fragments and restore function.

You can study the relative positions of the bones, muscles and nerves of the forearm in 3D atlas Humio - rotate the model to see each structure from any angle.