

viu.] THE MUSCLES. 297 



The extensor carpi ulnaris springs from the external con- 

 dyle and from the ulna, and ends in a tendon going to the 

 fifth metacarpal. 



Extensor ossis metacarpi pollicis. This great stretcher of 

 the thumb arises from both the ulna and radius (on their 

 hinder aspect), and is inserted by a long tendon into the first 

 metacarpal. 



The extensor primi internodii pollicis is a small muscle 

 which springs from the membrane between the radius and 

 the ulna, and is inserted into the proximal phalanx of the 

 thumb, as the extensor secundi internodii (springing from 

 the back of the ulna) is inserted into its distal phalanx. 



The extensor indicis is a narrow muscle which takes origin 

 from the middle of the ulna behind, and is inserted into the 

 posterior surface of the second and third phalanges of the 

 index. 



Supinator brevis. A deep muscle thus named comes from 

 the outer condyle and upper part of the ulna, and is inserted 

 into the radius wrapping it round somewhat from behind. 



9. The MUSCLES OF THE HAND are numerous, but small. 

 The thumb (which has no perforated flexor) is provided with 

 a flexor brevis going from the carpus to the proximal pha- 

 lanx ; also an abductor from the trapezium to the proximal 

 phalanx, and an adductor (placed in the fold of skin between 

 the thumb and index digit), going to the same phalanx from 

 the middle metacarpal. Besides these there is an opponens, 

 which goes from the trapezium to the outer border of the 

 first metacarpal. 



The little finger has also an opponens, going from the 

 unciforme to the fifth metacarpal ; an abductor, from the pisi- 

 forme to the proximal phalanx ; and a flexor brevis, from the 

 unciforme to the same phalanx. 



Small muscles called interossei arise from the sides of the 

 metacarpals and go to the sides of the proximal phalanges. 

 When the back of the hand (the other muscles being dissected 

 off) is looked at, four (dorsal] interossei are seen ; one going 

 to each side of the middle digit, one to the radial side of the 

 index, and one to the ulnar side of the ring digit. When the 

 palm of the hand is looked at, three (palmar] interossei are 

 seen : one going to the ulnar side of the index digit, and two 

 to the radial side of the fourth and fifth digits respectively. 



10. The ABDOMINAL REGION of the body is invested by 

 three great sheets of muscle and membrane. The first of 

 these, the external oblique (Fig. 268, 6), springs from outside 



