630 



MAMMALIAN ANATOMY 



At the lower part of this surface of the shaft is an oblique groove 

 running downward and backward and applied to the corresponding 

 groove on the ulnar surface of the second metacarpal, forming with 

 it a canal for the radial artery as it runs through from the dorsal to 

 the palmar surface of the hand. 



FIG. 497. 

 Proximal End. 



With Second 

 Metacarpa/. 



Palmar Side. 



With Second 



Metacarpal. 



Dorsal Side. 



THIRD LEFT METACARPAL, RADIAL SURFACE OF BASE AND 



PART OF SHAFT. 



The dorsal surface of the base (Fig. 498) is continuous with the 

 dorsal surface of the shaft, and presents a depressed area which begins 

 widely above at the notch separating the two parts of the proximal 

 surface and fades out in a point below. On the radial side of this 

 depression is inserted the tendon of the extensor carpi radialis brevior 



muscle. 



FIG. 498. 

 Proximal End. 



With Magnum. 



With Second Metacarpal. 



Radial Side. 



With Unciform. 



With Fourth 

 Metacarpal. 



Ulnar Side. 



THIRD LEFT METACARPAL, DORSAL SURFACE OF BASE AND 

 PART OF SHAFT. 



The Shaft presents few peculiarities. It is straighter than the 

 shaft of the other metacarpals, and its widest part is at the middle. 

 The palmar border is but faintly indicated, and gives origin in its 

 upper part to the second palmar interosseous muscle. To the radial 

 and ulnar sides of the shaft are attached the second and the third 

 dorsal interosseous respectively. 



