504 THE MUSCULATURE 



The subscapularis is an adductor when the arm is abducted. The inferior 

 part of the serratus anterior and the trapezius are important 

 in abduction of the arm. 

 {d) To adduct it, 



When the arm is at the side: pectorahs major, latissimus dorsi, deltoid (pos- 

 terior and anterior parts), teres major, triceps, coracobrachiahs, 

 short head of biceps, teres minor, infraspinatus. 



When the arm is abducted: pectorahs major, latissimus dorsi, teres major, 

 triceps, subscapularis, deltoid (dorsal and ventral parts), 

 coracobrachiahs. 

 (e) To rotate it lateralward (supinate), 



When the arm is at the side: infraspinatus (upper part), the dorsal part of 

 the deltoid, teres minor, supraspinatus. 



When the arm is abducted 60°: teres minor, infraspinatus, deltoid (dorsal 

 part), coracobrachiahs. 

 (/) To rotate it medialward (pronate). 



With the arm at the side: latissimus dorsi, pectoralis major, subscapularis, 

 deltoid (ventral part), long head of biceps, teres major, short 

 head of biceps. 



With the arm abducted 60°: latissimus dorsi, pectoralis major, subscapularis, 

 teres major, deltoid (ventral part). 



When the arms are raised high the power of rotation at the shoulder becomes 

 slight. 



15. Muscles acting on the forearm at the elbow-joint (arranged according to R. Fick). 



(a) Flexion at elbow. 



Forearm supinated: brachialis, long head of biceps, short head of biceps, 

 brachio-radialis, pronator teres, extensor carpi radialis longus, 

 flexor carpi radialis, extensor carpi radialis brevis, palmaris 

 longus. 

 Forearm in mid-position or pronated: brachialis, long head of biceps, short 

 head of biceps, brachio-radialis, extensor carpi radialis longus, 

 pronator teres, flexor carpi radialis, extensor carpi radialis 

 brevis, palmaris longus. 



{h) Extension at elbow: triceps (lateral, medial, and long heads), anconeus. 



(c) Pronation of forearm. 



Forearm extended: flexor carpi radiaUs, pronator teres, pronator quadratus, 

 palmaris longus. 



Forearm at right angles: pronator teres, flexor carpi radiahs, brachio-radialis, 

 pronator quadratus, extensor carpi radialis longus, palmaris 

 longus. 



Forearm flexed: pronator teres, brachio-radiahs, flexor carpi radialis, pro- 

 nator quadratus, extensor carpi radiahs longus, palmaris 

 longus. 



(d) Supination. 



Forearm extended: short head of biceps, supinator, long head of biceps, 

 brachio-radialis, extensor carpi radialis longus, abductor 

 poUicis longus, extensor pollicis brevis, extensor pollicis longus, 

 extensor indicis proprius. 



Forearm at right angles: short head of biceps, long head of biceps, supina- 

 tor, abductor pollicis longus, extensor pollicis brevis, brachio- 

 radialis (in pronation), extensor poUicis longus, extensor 

 indicis proprius. 



Forearm flexed: short head of biceps, long head of biceps, supinator, ab- 

 ductor pollicis longus, extensor pollicis brevis, extensor pollicis 

 longus, extensor indicis proprius. 



16. Muscles acting on the hand at the wrist (arranged according to R. Fick). 



(a) To flex it: flexor digitorum sublimis, flexor digitorum profundus, flexor 

 carpi ulnaris, flexor pollicis longus, flexor carpi radialis, ab- 

 ductor pollicis longus, palmaris longus. 



{b) To extend it: extensor digitorum communis, extensor carpi ulnaris, extensor 

 carpi radialis longus and brevis, extensor indicis proprius, 

 extensor pollicis longus. 



(c) Radial abduction: extensor carpi radialis longus, extensor carpi radialis 

 brevis, abductor pollicis longus, flexor carpi radialis, extensor 

 indicis proprius, extensor pollicis longus, extensor polhcis brevis. 



{d) Ulnar abduction: extensor carpi ulnaris, flexor carpi ulnaris. 



17. Muscles acting on the palm: 



(a) Toiflex the ulnar side: opponens, long and short flexors of the little finger. 



(6) To extend the ulnar side: extensor carpi ulnaris, extensor digiti quinti. 



(c) To adduct the ulnar side: third volar interosseous. 



{d) To abduct the ulnar side: abductor digiti quinti. 



For action on the radial side see "muscles adting on the thumb." Move- 

 ments of the second, third and fourth metacarpals are produced 

 by the long flexors and the dorsal interosseous muscles. 



18. Muscles acting on the thumb. 



(a) To oppose the thumb: adductor, opponens, flexor brevis, flexor longus, ad- 

 ductor brevis. 

 (6) To repose the thumb: long abductor, short extensor. 



