238 



THE MUSCLES OF THE UPPER LIMB. 



The abductor minimi digiti muscle arises by tendinous fibres from the lower 

 border and inner surface of the pisiform bone, and is inserted into the base of the 

 first phalanx of the little finger on the ulnar border, a slip being sent to the extensor 

 tendon on the back. 



The flexor brevis minimi digiti, separated at its origin from the abductor 

 muscle by a small interval through which pass the deep palmar branches of the ulnar 

 nerve and artery, arises from the front of the annular ligament, and from the tip of 

 the hooked process of the unciform bone, and is inserted into the base of the first 

 phalanx of the little finger, in common with the preceding muscle. This muscle is 

 sometimes absent, or becomes incorporated with the abductor. 



RP. HAD. BREV 



Fig. 245. DORSAL VIEW OF THE OUTER 



PART OP THE HAND, SHOWING THE 

 DEEP HEAD OF THE SHORT FLEXOR 

 AND THE ADDUCTORS OF THE 

 THUMB. (GK D. T.) 



The two heads of the abductor 

 indicis have been taken away ; t, 

 interval through which the radial 

 artery passes. 



The opponens minimi 

 digiti muscle arises from the 

 annular ligament and the unci- 

 form process, and is inserted 

 into the ulnar side of the fifth 

 metacarpal bone in all its 

 length. It is usually divided 

 into two parts by a cleft 

 through which the deep 

 branches of the ulnar artery 

 and nerve pass. 



The INTEROSSEOUS MUS- 

 CLES occupy the intervals be- 

 tween the metacarpal bones. 

 They are seven in number, all 



of them more or less visible from the palmar aspect, and they are divided into two 

 sets, viz., those which are best seen on the dorsal aspect of the metacarpus, and 

 those which are seen only in the palm. Their disposition is most easily understood 

 by reference to their action. 



The dorsal interosseous muscles abduct the fingers from the middle line of the 

 hand ; they are four in number, one in each of the spaces between the metacarpal 

 bones, and are numbered from without inwards. Each muscle arises from both the 

 metacarpal bones between which it is placed, but most extensively from that sup- 

 porting the finger upon which it acts, and the fibres converge pinnately to a common 

 tendon in the middle. Each terminates in a tendon which is inserted partly into 

 the base of the. first phalanx, and partly into the tendon of the extensor muscle on 

 the dorsum of the same part of the finger. Two of the muscles are inserted into 

 the middle finger and draw it to either side ; of the remaining two, one passes to the 

 radial side of the index finger, and the other to the ulnar side of the ring finger ; 

 they withdraw those fingers from the middle line of the hand. 



The first dorsal interosseous muscle or abductor indicis is larger than the others ; 

 its outer and larger head of origin arises from the proximal half of the ulnar border 

 of the first metacarpal bone, the inner is attached to the whole length of the second 



