Flexor-pronator compartment
The superficial flexor-pronator muscles arise predominantly from the common flexor origin at the medial epicondyle.
Pronator teres
- Origin: medial epicondyle and coronoid process
- Insertion: lateral surface of mid-radius
- Action: pronation; assists elbow flexion
- Nerve: median nerve
Flexor carpi radialis
- Origin: medial epicondyle
- Insertion: bases of second and third metacarpals
- Action: wrist flexion and radial deviation
- Nerve: median nerve
Palmaris longus
- Origin: medial epicondyle
- Insertion: palmar aponeurosis and flexor retinaculum
- Action: weak wrist flexion; tensions palmar fascia
- Nerve: median nerve
Flexor carpi ulnaris
- Origin: medial epicondyle, olecranon and posterior ulna
- Insertion: pisiform, hook of hamate and base of fifth metacarpal
- Action: wrist flexion and ulnar deviation
- Nerve: ulnar nerve
Flexor digitorum superficialis
- Origin: humeroulnar and radial heads
- Insertion: sides of middle phalanges of index to little fingers
- Action: PIP flexion
- Nerve: median nerve
Deep flexor compartment
Flexor digitorum profundus
- Origin: proximal ulna and interosseous membrane
- Insertion: bases of distal phalanges
- Action: DIP flexion
- Nerve: anterior interosseous nerve to index and middle; ulnar nerve to ring and little fingers
Flexor pollicis longus
- Origin: anterior radius and interosseous membrane
- Insertion: base of distal phalanx of thumb
- Action: thumb IP flexion
- Nerve: anterior interosseous nerve
Pronator quadratus
- Origin: distal ulna
- Insertion: distal radius
- Action: pronation and distal radioulnar joint stabilisation
- Nerve: anterior interosseous nerve
Extensor-supinator compartment
The common extensor origin is at the lateral epicondyle.
Superficial muscles include extensor carpi radialis brevis, extensor digitorum, extensor digiti minimi and extensor carpi ulnaris. Deep muscles include supinator, abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus and extensor indicis.
Clinical relevance
- Lateral epicondylitis principally involves the common extensor origin, especially ECRB.
- Medial epicondylitis involves the flexor-pronator origin.
- Tendon transfers depend on understanding muscle excursion, strength and line of pull.
References
- Orthobullets. Forearm Anatomy.