224 



MUSCLES OF THE UPPER LIMB. 



fibres end in a tendon, which occupies the narrow oblique groove in the 

 middle of the posterior surface of the carpal end of the radius, and is bound 

 down in a separate compartment of the annular ligament ; it is inserted 

 into the base of the terminal phalanx of the thumb. 



The groove which lodges the radial extensors of the carpus intervenes between 

 those which lodge the tendon of this muscle and the tendons of the other extensors 

 of the thumb. 



A part of the tendon of the extensor ossis metacarpi is often found to terminate in 

 the upper end of the abductor pollicis. The extensor primi internodii is not unfre- 

 quently united with the extensor of the metacarpal bone, only a slender tendinous 

 filament reaching the first phalanx. A portion of the extensor secundi internodii has 

 been found attached to the first phalanx. 



Fig. 184. Fig. 184. SUPERFICIAL MUS- 



CLES AND TENDONS ON THE 

 BACK OF THE WRIST AND 

 HAND (After Bourgery). i 



The posterior annular liga- 

 ment of the wrist is represented. 

 1, lower part of the extensor ossis 

 metacarpi pollicis ; 1', its inser- 

 tion ; 2, extensor primi inter- 

 nodii pollicis ; 2', its insertion ; 

 3, 3', tendon of the extensor se- 

 cundi internodii pollicis ; 4, 

 lower part of the extensor corn- 

 munis digitorum, before passing 

 below the posterior annular 

 ligament; 4', slip of this tendon 

 descending on the dorsum of 

 the middle finger, where it re- 

 ceives the insertion of the se- 

 cond and third dorsal inter- 

 ossei ; 4", division of the tendon 

 into three portions, of which the 

 median is inserted into the 

 second phalanx, the two lateral 

 passing on to be inserted into 

 the terminal phalanx ; the 

 union of the tendons of the 

 third, fourth, and fifth fingers is 

 shown ; the slighter union which 

 frequently exists between the 

 tendons of the second and third 

 fingers is not represented in 

 the figure j 5, extensor minimi 

 digiti ; 5', its junction with the 

 slip of the common extensor ; 



6, placed on the lower end of the ulna, points to the extensor carpi ulnaris ; 6', insertion 

 of this muscle into the base of the fifth metacarpal bone ; 7, part of the flexor carpi ulnaris ; 

 8, placed on the os magnum, points to the insertion of the extensor carpi radialis brevior ; 

 8', placed on the base of the second metacarpal bone, points to the insertion of the 

 extensor carpi radialis longior ; 9, tendon of the extensor indicis, emerging from below the 

 annular ligament, to pass towards the index finger; 10, small part of the adductor 

 pollicis, and deep head of the flexor brevis pollicis ; 11, first dorsal interosseous or abductor 

 indicis : in the other three interosseous spaces are seen in succession from the radial side 

 inwards the insertion of the first palmar, second dorsal, third dorsal, second palmar, 

 fourth dorsal, and third palmar interossei muscles ; 12, abductor minimi digiti. 



The extensor indicis (indicator) arises from the posterior surface of the 

 ulna for three or four inches below the middle. The tendon passes with 



