MUSCLES OF THE HAND. 



241 



Fig. 127 * 



Fig. 12S.f 



phalanx and aponeurotic expansion of tne extensor tendon of the same 

 linger. The first belongs to the index finger; the second to the ring 

 linger; and the third to the little finger; the middle finger being ex- 

 cluded. 



Relations. By their palmar surface with the flexor tendons and with 

 the deep muscles in the palm of the hand. By their dorsal surface with 

 the dorsal interossei. On one side with the metacarpal bone, on the other 

 with the corresponding dorsal interosseous. 



DORSAL INTEROSSEI. On turning to the dorsum of the hand, the four 

 dorsal interossei are seen in the four spaces between the metacarpal bones. 

 They are bipenniform muscles and arise by two heads, from the adjoining 

 sides of the base of the metacarpal bones. They are inserted into the base 

 of the first phalanges, and aponeurosis of the extensor tendons. 



The first is inserted into the index finger, and from its use is called 

 abductor indicis,J the second and third are inserted into the middle finger 

 compensating its exclusion from the palmar group ; the fourth is attached 

 to the ring finger ; so that each finger is provided with two interossei, 

 with the exception of the little finger, as may be shown by means of a 

 table, thus : 



one dorsal (abductor indicis), 

 one palmar. 

 Middle finger, two dorsal. 



n - { one palmar, 



Ring finger* \ 



' one dorsal. 



Little finger, remaining palmar. 



Relations. By their dorsal surface with a thin aponeurosis which sepa'- 

 ates them from the tendons on the dorsum of the hand. By their palmar 



* Palmar interossei. 1. Adductor indicis. 2. Abductor annularis. 3. luterosseoui 

 auricularis. 



f Dorsal interossei. 1. Abductor indicis. 2. Abductor medii. 3. Adductor medii. 

 4. Adductor annularis. 



t Homer divides this muscle and calls one portion of it abductor indicis and the other 

 prior indicis. Wilson's description is the best, as it makes the analogy between the foot 

 and hand complete, whilst there is a great discrepancy in Horner's mode of describing 

 them. G. 



21 Q 



Index finger, 



