35 



APPLIED ANATOMY. 



developed in the tendon of the flexor carpi ulnaris muscle. The anterior end of the 

 navicular (scaphoid) has on its palmar surface a tuberosity which can be felt immedi- 

 ately below the flexor carpi radialis tendon at the wrist ; this tendon passes along the 

 palmar surface to insert in the base of the second metacarpal bone (Fig. 360). 



The lower row, beginning on the radial side, is composed of the trapezium, 

 trapezoid, os magnum, and unciform. The first three articulate with the first three 

 metacapal bones but the unciform, like the cuboid in the foot, articulates with two 

 metacarpal bones the fourth and fifth. 



The trapezium articulates with the first metacarpal bone by a saddle-shaped joint 

 and has on its palmar surface a ridge. Along the inner side of this ridge runs the 



Posterior radial or thecal t 



Ulna 



Head of ulna 



>tyloid process of ulna 

 smilunar 



uneiform 



xtensor carpi ulnaris 



s magnum 



nciform 



FIG. 361. Posterior view of the bones of the carpus and metacarpus, showing the insertion of the three carpal 



extensor muscles. 



flexor carpi radialis tendon. The ridge of the trapezium and tuberosity of the navicu- 

 lar (scaphoid) give attachment to the radial side of the anterior anmdar ligament. 



The unciform bone has a hook-like (unciform) process on its palmar surface. It 

 can be felt by deep pressure 2 cm. (about ^ in. ) below and to the radial side of the 

 pisiform bone. This process and the pisiform bone give attachment to the ulnar side 

 of the anterior annular ligament. 



The Metacarpal Bones. The metacarpal bones have their bases at the 

 carpus and their heads toward the phalanges. The shafts are small as compared with 

 the extremities, and hence are not infrequently fractured. On each side of the head 

 is a small projecting tubercle, which, when the bone becomes luxated, catches in the 

 tissues and hinders reduction. 



On the palmar surface of the base of the second metacarpal bone is inserted the 

 flexor carpi radialis and into the base of the fifth the flexor carpi nlnaris, which is 

 continued onward from the pisiform bone. On the dorsal surface, into the base of the 



