496 THE MUSCLES AND FASCIA. 



metacarpal space, the metacarpal bone, and the Flexor tendons of the little 

 finger. 



Nerves. All the muscles of this group are supplied by the ulnar nerve. 



Actions. The Abductor minimi digiti abducts the little finger from the middle 

 line of the hand. It corresponds to a dorsal interosseous muscle. It also assists 

 in flexing the proximal phalanx. The Flexor brevis minimi digiti abducts the 

 little finger from the middle line of the hand. It also assists in flexing the 

 proximal phalanx. The Opponens minimi digiti draws forward the fifth meta- 

 carpal bone, so as to deepen the hollow of the palm. The Palmaris brevis corrugates 

 the skin on the inner side of the palm of the hand. 



Middle Palmar Region. 



Lumbricales. Interossei palmares. 



Interossei dorsales. 



The Lumbricales (Fig. 316) are four small fleshy fasciculi, accessories to the 

 deep Flexor muscle. They arise by fleshy fibres from the tendons of the deep 

 Flexor : the first and second, from the radial side and palmar surface of the tendons 

 of the index and middle fingers ; the third, from the contiguous sides of the ten- 

 dons of the middle and ring fingers ; and the fourth, from the contiguous sides of 

 the tendons of the ring and little fingers. They pass to the radial side of the 

 corresponding fingers, and opposite the metacarpo-phalangeal articulation each 

 tendon terminates in a broad aponeurosis which is inserted into the tendinous 

 expansion from the Extensor communis digitorum, covering the dorsal aspect of 

 each finger. 



The Interossei muscles are so named from occupying the intervals between 

 the metacarpal bones. They are divided into two sets, a dorsal and palmar ; the 

 former are four in number, one in each metacarpal space ; the latter, three in 

 number, lie upon the metacarpal bones. 



The Dorsal interossei are four in number, larger than the palmar, and occupy 

 the intervals between the metacarpal bones. They are bipenniform muscles, 

 arising by two heads from the adjacent sides of the metacarpal bones, but more 

 extensively from that side of the metacarpal bone which corresponds to the side 

 of the finger in which the muscle is inserted. They are inserted into the bases 

 of the first phalanges and into the aponeurosis of the common extensor tendon. 

 Between the double origin of each of these muscles is a narrow triangular interval, 

 through the first of which passes the radial artery ; through the other three passes 

 a perforating branch from the deep palmar arch. 



The First dorsal interosseous muscle, or Abductor indicis, is larger than the 

 others. It is flat, triangular in form, and arises by two heads, separated by a 

 fibrous arch, for the passage of the radial artery from the dorsum to the palm of 

 the hand. The outer head arises from the upper half of the ulnar border of the 

 first metacarpal bone ; the inner head, from almost the entire length of the radial 

 border of the second metacarpal bone ; the tendon is inserted into the radial side 

 of the index finger. The second and third dorsal interossei are inserted into the 

 middle finger, the former into its radial, the latter into its ulnar side. The fourth 

 is inserted into the ulnar side of the ring finger. 



The Palmar interossei, three in number, are smaller than the Dorsal, and placed 

 upon the palmar surface of the metacarpal bones, rather than between them. 

 They arise from the entire length of the metacarpal bone of one finger, and are 

 inserted into the side of the base of the first phalanx and aponeurotic expansion 

 of the common extensor tendon of the same finger. 



The first arises from the ulnar side of the second metacarpal bone, and is 

 inserted into the same side of the index finger. The second arises from the radial 

 side of the fourth metacaVpal bone, and is inserted into the same side of the ring 

 finger. The third arises*" *rom the radial side of the fifth metacarpal bone, and is 

 inserted into the same side of the little finger. From this account it may be seen 



