Forearm - Anterior, Superficial

Bones

Humerus Radius Ulna Hand

Superficial Layer of Anterior Forearm

The muscles of the anterior superficial forearm muscles are innervated by the median and ulnar nerves.

Flexor carpi ulnaris has two heads

Humeral head originates on the medial epicondyle of the humerus
Inserts on medial carpals (specifically, pisiform and hook of hamate) and base of metacarpal V
Flexes and adducts the hand and flexes the forearm.

Flexor carpi radialis

Originates from the medial epicondyle of the humerus
Inserts on the bases of metacarpals II and III
Flexes and abducts the hand and flexes the forearm.

Pronator teres two heads

Humeral head originates on the medial epicondyle of the humerus;
Ulnar head originates on the coronoid process of the ulna
Pronator teres inserts mid-shaft of the lateral radius
Pronates and flexes the forearm (no action on the wrist).

Palmaris longus

Originates on the medial epicondyle of humerus
Inserts into the palmar aponeurosis
Flexes the forearm and hand (variable).
Lies superficially in the palm.

Brachioradialis

Originates on the lateral supracondylar ridge of the humerus
Inserts on the base of the styloid process of the radius
Flexes the forearm.

Brachioradialis is often considered a posterior forearm muscle (due to its posterior origin), we include it in this anterior section because it is most visible anteriorly and, like the other muscles drawn in this tutorial, it flexes the forearm.* Along with its posterior origin, it is innervated by the radial (not the median or ulnar) nerve.*

Key points:

Because they cross the wrist, flexor carpi ulnaris, flexor carpi radialis, and palmaris longus all flex the hand at the wrist (in addition to flexing the forearm).
Because flexor carpi ulnaris inserts on the medial side of the carpals, it adducts the hand (brings it closer to the midline of the body).
Because flexor carpi radialis inserts more laterally, it abducts the hand (moves it away from the midline of the body)
Pronator teres is the only muscle to insert within the forearm, and the only superficial muscle to pronate the forearm (in addition to flexing the forearm).
The flexor retinaculum is a strap-like band of connective tissue that attaches to the medial and lateral carpals to form the "carpal tunnel;" it holds the tendons of the hand flexors in place. Compression of the median nerve in the carpal tunnel causes carpal tunnel syndrome.
Medial epicondylitis (aka, Golfer's elbow) results from inflammation of the common flexor tendon on the medial epicondyle of the humerus and subsequent compression of the ulnar nerve (cubital tunnel syndrome).

Brachial Plexus

Forearm - Anterior, Superficial

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