antebrachii

Antebrachii is the Latin term referring to the forearm, the region of the upper limb between the elbow and the wrist. In humans it contains the two long bones, the radius and ulna, connected by the interosseous membrane, as well as the muscles, nerves, vessels, and tendons that act on the hand and fingers.

Anatomy and organization

The forearm is divided into two compartments: the anterior (flexor-pronator) compartment and the posterior (extensor-supinator) compartment. The anterior compartment includes muscles such as pronator teres, flexor carpi radialis, flexor carpi ulnaris, palmaris longus, flexor digitorum superficialis, and the deeper flexors flexor digitorum profundus, flexor pollicis longus, and pronator quadratus. The posterior compartment contains the extensor and supinator muscles, including extensor carpi radialis longus and brevis, extensor digitorum, extensor digiti minimi, extensor carpi ulnaris, as well as the deep extensors like abductor pollicis longus, extensor pollicis brevis and longus, and the supinator.

Nerves and vessels

Nerve supply varies by compartment: most of the anterior compartment muscles are innervated by the median nerve (with some exceptions such as parts of flexor digitorum profundus), the posterior compartment by the radial nerve, and the deep layer of the flexors includes contributions from the anterior interosseous branch. The ulnar nerve supplies a portion of the forearm muscles in the medial aspect. Blood supply largely derives from branches of the ulnar and radial arteries, with accompanying veins and interosseous vessels.

Function and clinical notes

The forearm facilitates flexion, extension, pronation, and supination of the hand, and provides stabilization for wrist movements. Common injuries include fractures of the radius or ulna and nerve entrapments affecting the forearm, such as radial tunnel syndrome or anterior interosseous syndrome.