Anterior Forearm Muscles (Forearm Flexors)

The forearm (antebrachium) is the part of the arm between the elbow and the wrist. All the muscles in the forearm are divided into two compartments, the anterior and posterior. The anterior compartment contains all the muscles at the front of the forearm, that is, the side of the palm. The 8 muscles in the anterior compartment all act to flex the forearm and hand and thus are also known as the forearm flexors.

These muscles lay in different layers within the anterior aspect of the forearm, further classified into superficial, intermediate, and deep groups.

Muscle Name	Location Layer	Origin	Insertion	Action	Innervation
1. Pronator teres	Superficial	Medial epicondyle of the humerus via the common flexor tendon; The coronoid process of ulna	Lateral surface of radius	Pronating the forearm; Flexing the wrist	Median nerve (C6, C7)
2. Flexor carpi radialis	Superficial	Via common flexor tendon	2nd and 3rd metacarpal base	Flexing and abducting the wrist	Median nerve (C6, C7)
3. Palmaris longus	Superficial	Via common flexor tendon	Into the flexor retinaculum on its distal side	Tightening the grip of hand; Flexing the wrist	Median nerve (C6, C7)
4. Flexor carpi ulnaris	Superficial	Via common flexor tendon; The olecranon of ulna	Pisiform and hamate (carpal bones), and 5th metacarpal base	Flexing and abducting the wrist	Ulnar nerve (C7, C8, T1)
5. Flexor digitorum superficialis	Intermediate	Via common flexor tendon; The coronoid process of ulna; Anterior border of proximal radius	2nd to 5th middle phalangeal bases	Flexing the index finger to little finger	Median nerve (C6, C7, T1)
6. Flexor digitorum profundus	Deep	Anterior and medial surfaces of proximal ulna; Interosseous membrane	2nd to 5th distal phalangeal bases	Flexing the index finger to little finger, and the wrist (secondary)	Median nerve (C8 and T1); Ulnar nerve (C8 and T1)
7. Flexor pollicis longus	Deep	Anterior surface of radius; Interosseous membrane	Base of the distal phalanx of the thumb	Flexing the thumb	Anterior interosseous nerve (C8, T1)
8. Pronator quadratus	Deep	Anterior surface of distal ulna	Anterior surface of distal radius	Pornating the forearm	Anterior interosseous nerve (C8, T1)

All the muscles in the flexor group receive their blood supply from various branches of the ulnar and radial arteries.

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