170 DR. R. W. SHUFELDT ON [Apr. 1, 



iu each case into the base of the second, third, and fourth metacarpal 

 bones. Just beyond its origin this muscle is very tliick and fleshy, and 

 in this locahty fuses to some Httle extent with the supinator lotigus, 

 while at its insertion a thin tendinous expansion more or less unites 

 its slips of division, and spreads out over the back of the carpus. 



.38. Extensor carpi radialis. — Running parallel with the extensor 

 digitorum longus, this muscle likewise arises, tendinous, from the 

 external condyle of the humerus, and, as it approaches the carpus, it 

 forms a slender tendon which inserts itself into the os carpi radiale. 



This muscle has not more tiian a quarter the bulk of the extensor 

 digitorum longus, with which it is quite intimately connected along 

 its radial border. 



39. Extensor digitorum brevis. — Superficially, on the back of the 

 manus, we observe a divided set of muscles, which constitute the 

 short extensors of the phalanges. Five-parted, but each slip more 

 or less distinct, the extensor digitorum brevis arises from the dorsal 

 aspect of the five metacarpal bones at their proximal extremities, and 

 from the ossicles of the first row of the carpus. These slips are 

 fleshy over the back of the hand, but become tendinous, each one 

 at the bases of the digits, and a tendon runs along the back of each 

 phalanx to the base of the ungual joint, where it is, in each case, 

 inserted. 



Proximally, these muscular slips are imbricated, while distally 

 their tendons, as they pass over each jihalangeal joint in the fingers, 

 send down lateral tendinous slips on either side, which attach to the 

 sides of the heads of the finger-bones. 



40. Extensor carpi ulnaris. — Springing from the postero-external 

 aspect of the external condyle of the humerus, in common with the 



flexor carpi ulnaris, by a strong tendon, this muscle passes down 

 the side of the forearm ; when opposite the radial side of the wrist 

 it develo|)s a strong tendon which, passing between the muscles ol" 

 the hand on that side, finally inserts itself into the proximal end 

 of the fifth metacarpal, upon its external surface. 



41. TJlno-metacarpalis pollicis. — I propose this name for the 

 present muscle in lieu of the " Vlno-pollicialis dorsalis s. Abductor 

 pollicis longus " of Fiirbringer, or even the " M. ulno-metacurpialis 

 /" of Hoffmann. It is the Abductor pollicis longus of Stannius, 

 the E.ctensor ossis metacarpi jjoUicis of Mivart and Sanders. It 

 arises from the dorsal aspect of the lower third of the forearm ; 

 springing from the upper surface of the shaft of the ulna, it passes 

 obliquely across the carpus, to finally develop a strong little tendon 

 which is inserted into the proximal end of the pollex metacarpal, 

 upon its dorsal side. 



42. The fie.vor carpi ulnaris arises by two heads — one from 

 the posterior surface of the radial condyle of the humerus, and the 

 other from the side of the proximal extremity of the ulna and from 

 the olecranon process of that bone. These are at first strong tendons, 

 but soon become carneous and forming a flat, powerful muscle running 

 down the outer side of the forearm, which again becomes tendinous 

 at the wrist, to finally insert itself into the pisiform bone, upon the 



