Arm Muscle Anatomy

1. Muscle Abbr Action Nerve Root
Supraspinatus SS External rotation of arm Fixes Suprascapular C5 (6)
shoulder during loading
Infraspinatus IS External rotation of arm Suprascapular C5 (6)
Teres major TMa Internal rotation of arm Lower subscapular C6 (7)
Adduction
Extension
Pectoralis major PM Internal rotation of arm Lateral pectoral Medial C5 6
pectoral C7 8
Latissimus dorsi LD Adduction of arm Arises from cord C6 7 8
Deltoid D Abduction of arm Axillary C5 (6)
Serratus anterior SA Forward rotation of scapula Arises directly from C5 6 7
(absence produces “winging”) roots
Biceps BB Flexion of elbow Supination of Musculocutaneous C5 (6)
forearm (flexed)
Triceps T Extension of elbow Radial C(6) 7
Brachioradialis BR Flexion of elbow Radial C6
Pronator teres PT Pronation of forearm Median C6 7
(extended)
Pronator quadratus PQ Pronation of forearm (flexed) Ant.interosseous C7
(median)
Supinator S Supination of forearm Post.interosseous C6
(extended) (radial)
Flexor carpi radialis FCR Flexion of wrist Median C6 7

2. Extensor pollicis EPL Extension of IP joint of thumb Posterior interosseous C7 8
longus (with AP and APB) (radial)
Extensor pollicis EPB Extension of MP joint of Posterior interosseous C7 8
brevis thumb
Abductor pollicis APL Extension of CM joint of Posterior interosseous C7 8
longus thumb
Radial deviation of wrist
Extensor digitorum ED Extension of MP joints Posterior interosseous C7 (8)
Extensor indicis EI Extension of index Posterior interosseous C7 8
Extensor digiti minimi EDM Extension of small Posterior interosseous C7 8
Extensor carpi ulnaris ECU Extension of wrist Posterior interosseous C7 (8)
Ulnar deviation of wrist
Extensor carpi radialis ECRL Extension of wrist Radial C6 7
longus and brevis Radial deviation of wrist
ECRB
Flexor carpi ulnaris FCU Flexion of wrist Ulnar Ulnar C8
deviation of wrist
Palmaris longus PL - Median C8
Flexor digitorum FDS Flexion of PIP joints Median C7 8
superficialis
Flexor digitorum FDP Flexion of DIP joints Ant.intersseous (index C8
profundus and middle)
Ulnar (ring and small)
C8
Flexor pollicis longus FPL Flexion of thumb IP joint Ant.interosseous C8
Flexor pollicis brevis FPB Flexion of MP joint of thumb Median (superficial T1
head)
Ulnar (deep head)
Abductor pollicis APB Abduction of thumb (extension Median T1
brevis of IP joint)
Adductor pollicis AP Adduction of thumb (extension Ulnar T1
of IP joint)
Abductor digiti ADM Abduction of small finger Ulnar T1
minimi
Flexor digiti minimi FDM Flexion of MP joint of small Ulnar T1
finger
Interosseous Line of reference is axis of
middle finger
Dorsal Dorsal ABduct “DAB”
1st 1st DIO Abducts index finger Ulnar T1

3. 2nd 2nd DIO Abducts middle finger radially Ulnar T1
3rd 3rd DIO Abducts middle finger Ulnar T1
ulnarwards
4th 4th DIO Abducts ring finger Ulnar T1
Palmar Palmar ADduct “PAD”
1st 1st PIO Adducts index finger Ulnar T1
2nd 2nd PIO Adducts ring finger Ulnar T1
3rd 3rd PIO Adducts small finger Ulnar T1