1 14 



ANATOMY IN A NUTSHELL. 



Origin. Tendons of deep flexor. (Plate XXXI.) 



[nsertion.- Tendinous expansion from Extensor communis digitorum on 

 hack of each finger. 



\i i ion. To flex firsl phalanges. 



Nerve Si pply. The two outer Lumbricales by the sixth cervical 

 through the third and fourth digital branches of the median; the two inner by 

 the eighth cervical through deep palmar branch of ulnar. The third lnm- 

 brical receives the median in almost half the cases. 



Blood Si pply.— From digital branches of the superficial palmar arch 

 and the interosseous branches of the deep palmar arch. 



Dorsal Interossei. — Description. — ( 1 dates | XXXI Y-XXX [II.) —These 

 small muscles, four in number, occupy the intervals between the metacarpal 

 bones. They are bipenniform. Between the double origin of each is a narrow 

 triangular interval, through the firsl of which passes the radial artery; through 

 each of the miter three passes a perforating branch from the deep palmar arch. 



The Abductor indicis or the Firsl dorsal interosseous is the largest of these 

 muscles. 



Origin. — by two heads; (1) Outer head from upper half of ulnar border 

 of first metacarpal hone. ('_') Inner head from almost the whole length of the 

 radial border of the second metacarpal bone. (Plate XXVI.) 



Insertion. Into the radial side of base of first phalanx of index finger. 



'The Second dorsal interosseous. 



Origin. By two heads from the adjacent sides of the second and third 

 metacarpal. ( Plate XXVI. J 



Insertion into the radial side of the first phalanx of middle finger. 



The Third dorsal interosseous. 



ORIGIN. By two heads from the adjacent sides of the third and fourth meta- 

 carpal bones. (Plate XXVI.) 



Insertion. -Into the ulnar side of the firsl phalanx of middle finger. 



The Fourth dorsal interosseous. 



Origin. By two heads from the adjacent sides of the fourth and fifth meta- 

 carpal bones. (Plate XXVI.) 



Insertion. Into the ulnar side of the first phalanx of ring finger. 



Action. (1) Extend the last two phalanges. (2) Flex the metacarpo- 

 phalangeal joints, (3) Ahdnct the fingers. 



Blood Supply. From deep palmar and posterior carpal arches. 



Nerve Supply. Deep branches of the ulnar nerve. 



The Palmar interossei which are placed on the palmar surface of the sec- 

 ond. Fourth and fifth metacarpal bones are three in number. Their insertion 

 besides being into the bone is into the aponeurotic expansion ^( the common 

 tendon of the same finger, the same as the dorsal interossei. (Plate XXXV.) 



Firsl palmar interosseous. 



Origin. By one head from the ulnar side of the second metacarpal hone. 



Insertion. Into the ulnar side of the firsl phalanx of index finger. 



Second palmar interosseous. 



< >RIGIN. By one head from the radial side of the fourth metacarpal hone 



