CARPO-MET A CARPAL. 



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bones, and, passing between the bones of the second range, lines the carpal extre- 

 mities of the four inner metacarpal bones. The fourth lines the adjacent 

 surfaces of the trapezium and metacarpal bone of the thumb. And the fifth the 

 adjacent surfaces of the cuneiform and pisiform bones. 



Actions. The movement permitted in the carpo-metacarpal articulations 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 

 thumb with the trapezium is most movable, then the fifth metacarpal, and then 

 the fourth. The second and third are almost immovable. In the articulation of 

 the metacarpal bone of the thumb with the trapezium, the movements permitted 

 are flexion, extension, adduction, abduction, and circumduction. 



Fig. 136. Vertical Section through the Articulations at the Wrist, showing the five Synovial 



Membranes. 



The carpal extremities of the metacarpal bones articulate with one another at 

 each side by small surfaces covered with cartilage, 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 lining the lateral facets is a reflection from that 

 between the two rows of carpal bones. 



The digital extremities of the metacarpal bones are connected together by a 

 narrow fibrous band, the transverse ligament, which passes transversely across 

 their under surfaces, and is blended with the ligaments of the metacarpo-phalan- 

 geal articulations. Its anterior surface presents four grooves for the passage of 

 the flexor tendons. ( Its posterior surface blends with the ligaments of the meta- 

 carpo-phalangeal articulation. 



