Pronator Teres:Humeral and Ulnar heads

(Median nerve passes between heads)

Flexor compartment of the forearm: Superficial layer

Attachments:Proximal:

Humeral head: medial epicondyle of humerus Ulnar head: coronoid process of ulna

Distal: lateral mid-shaft of radius

Action: pronate forearm (also; stabilize + flex elbow) PERIPHERAL NERVE + spinal cord level of origin:

median nerve: C6,7,8, T1Spinal segments: C6,7

Flexor carpi radialis (FCR)

Flexor compartment of the forearm: Superficial layer

Attachments:Proximal: medial epicondyle of humerusDistal: base of 2nd metacarpal

Action: flex + RD wrist jt. (also; stabilize + flex elbow) PERIPHERAL NERVE + spinal cord level of origin:

median nerve: C6,7,8, T1Spinal segments: C6,7

Palmaris longus(frequently absent)

Flexor compartment of the forearm: Superficial layer

Attachments:Proximal: medial epicondyle of humerusDistal: palmar aponeurosis

Action: flex wrist (tense palmar fascia for grasp) (also; stabilize + flex elbow) PERIPHERAL NERVE + spinal cord level of origin:

median nerve: C6,7,8, T1Spinal segments: C7,8

Flexor carpi ulnaris (FCU):Humeral and Ulnar heads

(Ulnar nerve passes between the heads)

Flexor compartment of the forearm: Superficial layer

Attachments:Proximal:

Humeral head: medial epicondyle of humerus Ulnar head: olecranon process of ulna

Distal: Humeral head: hook of hamate Ulnar head: base of 5th metacarpal

Action: flex + UD wrist jt. (also; stabilize + flex elbow) PERIPHERAL NERVE + spinal cord level of origin:

ulnar nerve: C8, T1Spinal segment: C8

Flexor digitorum superficialis (FDS):Humeral-Ulnar and Radial heads

Flexor compartment of the forearm: Intermediate layer

Attachments:Proximal:

Humeral-Ulnar head: medial epicondyle of humerus + coronoid process of ulna

Radial head: proximal radiusDistal: shaft of MIDDLE phalanx of digits 2-5 (note the split tendon)

Action: flex PIP jt. of digits 2-5 (assist in MP flex + wrist flex)PERIPHERAL NERVE + spinal cord level of origin:

median nerve: C6-T1Spinal segments: C7, 8, T1

Flexor digitorum profundus (FDP)

Flexor compartment of the forearm: Deep layer

Attachments:Proximal: ulna (anteromedial shaft + interosseous membrane)Distal: base of DISTAL phalanx of digits 2-5

Action: flex DIP of digits 2-5. Assist flex of PIP, MP, and wrist

PERIPHERAL NERVE + spinal cord level of origin: median nerve to digits 2 + 3. Ulnar nerve to digits 4 + 5Spinal segments: C8, T1

Flexor pollicis longus (FPL)

Flexor compartment of the forearm: Deep layer

Attachments:Proximal: radius (anterior shaft + interosseous membrane)Distal: base of DISTAL phalanx of thumb

Action: Flex IP of thumb. Assist flex of MP, CM PERIPHERAL NERVE + spinal cord level of origin:

median nerve: C6, 7, 8, T1Spinal segments: C8, T1

Pronator quadratus

Flexor compartment of the forearm: Deep layer

Attachments:Proximal: distal ulna (anterior)Distal: distal radius (anterior)

Action: pronate forearm PERIPHERAL NERVE + spinal cord level of origin:

median nerve: C6, 7, 8, T1 Spinal segments: C8, T1

Extensor carpi radialis longus (ECRL)

Extensor compartment of the forearm: Superficial layer

Attachments:Proximal: lateral supracondylar ridge of humerus Distal: base of 2nd metacarpal

Action: extend + RD wrist (synergist with FCR to get pure RD) PERIPHERAL NERVE + spinal cord level of origin:

radial nerve: C5-T1Spinal segments: C6,7

Extensor carpi radialis brevis (ECRB)

Extensor compartment of the forearm: Superficial layer

Attachments:Proximal: lateral epicondyle of humerusDistal: base of 3rd metacarpal

Action: extend wrist (more central to axis to get pure extension) PERIPHERAL NERVE + spinal cord level of origin:

radial nerve: C5-T1Spinal segments: C6,7

Extensor digitorum (ED)(sometimes includes the term

‘communis’ – EDC)

Extensor compartment of the forearm: Superficial layer

Attachments:Proximal: lateral epicondyle of humerusDistal: dorsal apparatus of digits 2-5

Action: extend MP jt. 2-5 (synergist to extend PIP + DIP + assist wrist extension) PERIPHERAL NERVE + spinal cord level of origin:

radial nerve: C5-T1 Spinal segments: C6,7,8

Extensor digiti minimi (EDM)

Extensor compartment of the forearm: Superficial layer

Attachments:Proximal: lateral epicondyle of humerusDistal: dorsal apparatus of digit 5

Action: extend MP jt. of 5 (synergist to extend PIP + DIP) PERIPHERAL NERVE + spinal cord level of origin:

radial nerve: C5-T1Spinal segments: C7,8

Extensor carpi ulnaris (ECU)

Extensor compartment of the forearm: Superficial layer

Attachments:Proximal: lateral epicondyle of humerus + posterior ulnaDistal: base of 5th metacarpal

Action: extend + UD wrist (synergist with FCU to get pure UD) PERIPHERAL NERVE + spinal cord level of origin:

radial nerve: C5-T1 Spinal segments: C7,8

Supinator:This muscle wraps around

lateral elbow from post. to ant.

Extensor compartment of the forearm: Deep layer

Attachments:Proximal: lateral epicondyle of humerus + supinator fossa of ulnaDistal: proximal shaft of radius (in area of radial tuberosity)

Action: supinate forearm (proximal RU jt.) PERIPHERAL NERVE + spinal cord level of origin:

radial nerve: C5-T1 Spinal segments: C6

Abductor pollicis longus (APL)

Extensor compartment of the forearm: Deep layer

Attachments:Proximal: radius + ulna, interosseous membraneDistal: base of 1st metacarpal

Action: ABduct + extend CM jt of thumb PERIPHERAL NERVE + spinal cord level of origin:

radial nerve: C5-T1 Spinal segments: C7,8

Extensor pollicis brevis (EPB)

Extensor compartment of the forearm: Deep layer

Attachments:Proximal: radius, interosseous membraneDistal: base of PROXIMAL phalanx of thumb

Action: extend MP jt. of thumb (assist extension of CM jt.) PERIPHERAL NERVE + spinal cord level of origin:

radial nerve: C5-T1 Spinal segments: C7,8

Extensor pollicis longus (EPL)

Extensor compartment of the forearm: Deep layer

Attachments:Proximal: ulna, interosseous membraneDistal: base of DISTAL phalanx of thumb

Action: extend IP jt. of thumb (assist extension of MP + CM jts.) PERIPHERAL NERVE + spinal cord level of origin:

radial nerve: C5-T1Spinal segments: C7,8

Extensor indicis (EI)

Extensor compartment of the forearm: Deep layer

Attachments:Proximal: ulna, interosseous membraneDistal: dorsal apparatus of index finger

Action: extend MP jt. of index finger (synergist to extend PIP + DIP jts.) PERIPHERAL NERVE + spinal cord level of origin:

radial nerve: C5-T1 Spinal segments: C7,8