CARPOMETA CARPAL ARTICULA TIONS 



319 



The synovial membranes of the wrist and carpus (Fig. 256) are thus seen to be five in number. 

 The first, the membrana sacciformis of the inferior radioulnar articulation, passes from the 

 lower end of the ulna to the sigmoid cavity of tKe radius, and lines the upper surface of the 

 articular disk. The second passes from the lower end of the radius and articular disk above 

 to the bones of the first row below. The third, the most extensive, passes between the contig- 

 uous margins of the two rows of carpal bones between the bones of the second row to the 

 carpal extremities of the four inner metacarpal bones. The fourth passes from the margin of 

 the trapezium to the metacarpal bone of the thumb. The fifth passes between the adjacent 

 margins of the cuneiform and pisiform bones. 



Movements. The movement permitted in the carpometacarpal articulations of the four 

 inner fingers is limited to a slight gliding of the articular surfaces upon each other, the extent 

 of which varies in the different joints. Thus, the articulation of the metacarpal bone of the 

 little finger is most movable, then that of the ring finger. The metacarpal bones of the index 

 and middle fingers are almost immovable. 



EPIPHYSEAL 

 JUNCTION 



MEMBRANA SACCI- 

 FORMIS OF INFERIOR 

 RAOIO-ULNAR 

 ARTICULATION 



TRIANGULAR 



ARTICULAR DISK 



STYLOID PROCESS 



OF ULNA 



EPIPHYSEAL 

 JUNCTION 



RADIOCARPAL 

 ARTICULATION 



INTEROSSEOUS 

 LIGAMENT 



INTEROSSEOUS 

 LIGAMENT 



INTERMETACARPAL 

 ARTICULATION 



INTERCARPAL 

 ARTICULATION 



ARTICULATION OF 

 TRAPEZIUM AND 

 METACARPAL BONE' 

 OF THUMB 



CARPOMETACARPAL 

 ARTICULATION 



METACARPAL BONES 



FIG. 256. Joints of the right hand, from the back of the hand. (Spalteholz.) 



3. ARTICULATIONS OF THE METACARPAL BONES WITH EACH OTHER (ARTICU- 

 LATIONES INTERMETACARPEAE (Figs. 254, 256). 



The carpal extremities of the four inner metacarpal bones articulate with 

 one another at each side by small surfaces covered with cartilages, and connected 

 by dorsal, palmar, and interosseous ligaments,. 



