ARTICULATIONS OF THE UPPER EXTREMITIES. 297 



of the base of the third metacarpal bone, and do not communi- 

 cate with each other, except through the proper carpal articu- 

 lation. The specification of this arrangement is overlooked by 

 anatomists generally. 



The Inferior Palmar Ligaments are three in number, and are 

 between the lower ends of the metacarpal bones of the fingers, 

 each one consists in a transverse fasciculus, placed between the 

 flexor tendons and the interosseous muscles, and on a level 

 with the anterior part of the first joint of the fingers. Their 

 more superficial fibres may be traced across the bones, and are 

 somewhat blended with the capsular ligaments; the more deep- 

 seated are short, and pass from one bone to the other. 



Of the Metacarpo-Phalangial Articulations. 



These are formed by the lower ends of the metacar.pal bones, 

 and the upper ends of the first phalanges. Each one presents 

 an anterior ligament, two lateral ones, and a synovial mem- 

 brane. 



The anterior Ligament* is a flat fibrous semicircle, on the 

 front of the articulation, of considerable thickness. It goes trans- 

 versely, and has its two extremities attached to the ridge on 

 either side of the articular margin of the metacarpal bone. Its 

 inferior margin descends a little, and comes in contact with the 

 synovial membrane. In front, many of its fibres are obtained 

 from the ligamento-cartilaginous sheath of the flexor tendons, 

 so that it may be considered as made by two planes the pal- 

 mar one facing towards the tendons, and forming the trochlea, 

 in which they play, and the other being next to the joint, and 

 continued to- the lateral ligaments. The thickness of the ante- 

 rior ligament, besides communicating great strength to the joint 

 is useful in removing the tendons from the line of motion of the 

 phalanges, and thereby giving increased power and delicacy of 

 motion to the muscles. Bichat considers himself to have first 

 indicated particularly this structure, which he thought was in- 

 tended to protect the articulation from the impression of the ten- 

 don: he ought to have added, in the firm grasping of bodies, and 

 to make the movements of the joint more delicate. On the sides 



* Bichat, loc. cit. 



