150 ANATOMY OF UPPER EXTREMITY, ETC. 



artery sends a metacarpal branch along the metacarpal 

 bone of the little finger. 



The DORSAL INTEROSSEOUS MUSCLES are four in number, 

 occupying the spaces between the metacarpal bones, and 

 arising by a double head from the lateral surfaces of the 

 two bones between which they lie. The first is larger than 

 the others, and is called the abductor indicts ; it is inserted 

 into the radial side of the first phalanx and. the extensor 

 tendon of the index finger ; the radial artery passes between 

 its heads ; the second terminates in the first phalanx and 

 extensor tendon of the middle finger on the radial side ; 

 the third is also inserted into the first phalanx and ex- 

 tensor tendon of the middle finger, but upon its ulnar 

 side ; the fourth is inserted into the first phalanx and ex- 

 tensor tendon of the ring finger on its ulnar side. 



DISSECTION IX. 



PALM OF THE HAND. 



To dissect tlie hand, the fingers and thumb should be separated 

 widely from each other and fastened to the table by pins driven 

 through the skin at the tip of each finger. An incision made down 

 the middle of the palm, and another transversely across the roots 

 of the fingers, from which others can be carried down the length of 

 each, will permit the removal of the thick skin and fat covering and 

 penetrating the perforations of the dense fascia radiating from the 

 annular ligament to the fingers. Upon the ulnar side the student 

 must respect the palmaris brevis muscle, composed of a few bundles 

 of transverse fibres lying in the fat just beneath the integument, and 

 he must be careful not to destroy the transverse ligament, which 

 Stretches between the commissures of the fingers. 



The PALMARIS BREVIS MUSCLE consists of a small though 

 variable number of transverse fibres, arising from the 

 palmar fascia and annular ligament ; it is inserted into 

 the integument of the ulnar border of the hand. 



The ulnar nerve, dividing on the annular ligament, sends 

 a superficial branch to the palmaris brevis and gives off 

 two digital nerves which supply both sides of the little 

 finger and the contiguous side of the ring finger. A deep 

 branch penetrates between the abductor and flexor minimi 

 digiti muscles, then passes under the flexor tendons, accom- 

 panying the deep palmar arch, and is distributed to the 



