322 



HUMAN ANATOMY. 



somewhat outward and inward, so as to broaden or narrow the socket. The distal 

 row of carpal bones presents a prominence made by the os magnum and the unci- 

 form, which are held firmly together so as to move nearly as one, fitting into the 

 socket presented by the first row. The outer side of this prominence is quite 

 straight, making an entering angle with the trapezoid, receiving the ridge between 

 the concavity and convexity of the scaphoid. At this point near the palmar surface 

 the OS magnum receives a ligament from the scaphoid, which may occasionally 

 deserve to be called interosseous. The pisiform has a capsular ligament enclosing 

 the joint between it and the cuneiform. 



The four bones of the second row are joined by three iiiterosseous ligaments : one 



Fig. 341. 



Ulna Interosseous membrane Radius 



Inferior dorsal radio-ulnar 

 ligament (relaxed) 



Dorsal transverse ligament 



- Dorsal /J// ////O/ 



carpo-metacarpal ligaments  / 'I II '\\K' 



Accessory bands 



Scapho-metacarpal 

 band 



Dorsal aspect of right wrist. 



between the trapezium and trapezoid, near the palm ; one between the trapezoid and 

 OS magnum, near the dorsum ; and one between the os magnum and unciform, much 

 the strongest, connecting the palmar halves of the bones at the distal end. None 

 of these interrupt the communication of the svnovial cavity of the intracarpal joint 

 and those at the bases of the metacarpals. The scaphoid, semilunar, and cuneiform 

 have very properly been compared to an intra-articular fibro-cartilage or meniscus, 

 subdividing a joint. No muscle of the forearm is inserted into them. (The flexor 

 carpi ulnaris, which has the pisiform as a sesamoid bone in its tendon, has its real 

 termination in the fifth metacarpal.) Hence this series is never directly moved, but 

 changes position under the pressure of the distal row, which is pulled against it 

 by the muscles moving it. It plays an important part in the movements of the 

 joint. 



