META C'ARPO-PHALAXGEAL ARTICULA TIONS. 



361 



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

 the trapezium to the metacarpal bone of the thumb. The fifth, between the 

 adjacent margins of the cuneiform and pisiform bones. 



Actions. The movement permitted in the carpo-metacarpal 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. 



Jletacarpo-phalangeal 

 articulation. 



3. ARTICULATION'S OF THE METACARPAL BOXES WITH EACH OTHER. 



The carpal extremities of the four inner metacarpal bones articulate with 

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

 together by dorsal, palmar, and interosseous ligaments. 



The Dorsal and Palmar Ligaments pass transversely from one bone to another 

 on the dorsal and palmar surfaces. The Interosseous Ligaments pass between 

 their contiguous surfaces, just beneath their lateral articular facets. 



The Synovial Membrane between the lateral facets is a reflection from that 

 between the two rows of carpal bones. 



The Transverse Metacarpal Ligaments (Fig. 252) is a narrow fibrous band which 

 passes transversely across the anterior surfaces of the digital extremities of the four 

 inner metacarpal bones, connecting 

 them together. It is blended an- 

 teriorly with the anterior (glenoid) 

 ligament of the metacar^al-phalan- 

 geal articulations. To its posterior 

 border is connected the fascia which 

 covers the Interossei muscles. Its 

 superficial surface is concave where 

 the flexor tendons pass over it. Be- 

 neath it the tendons of the Inter- 

 muscles pass to their insertion. 



X. Metacarpo-phalangeal Articu- 

 lations (Fig. 252). 



These articulations are of the 

 condyloid kind, formed by the re- 

 ception of the rounded head of the 

 metacarpal bone into a superficial 

 cavity in the extremity of the first 

 phalanx. The ligaments are 

 Anterior. 

 Two Lateral. 



The Anterior Ligaments (Gl * 

 Ligaments of Cruveilhier) are thick, 

 dense, fibrous structures, placed on 

 the palmar surface of the joints in 

 the intervals between the lateral 

 ligaments, to which they are con- 

 nected : they are loosely united to 

 the metacarpal bone, but very firmly 

 to the base of the first phalanges. 

 Their palmar surface is intimately 

 blended with the transverse metacar- 

 pal ligament, and presents a groove for 

 the passage of the flexor tendons, the 



Phalangeal 

 articulations. 



FIG. 252. Articulations of the phalanges. 



