200 THK ARTICULATIONS. 



Artkuhr surfaces. — The radial surface, elongated transversely and very 

 irreo-ular, presents : 1 . Outwardly, a wide groove, limited in front by a small 

 o-lenoid cavity, and bounded, posteriorly, by a non-articular excavation which 

 receives a prolongation of the second bone in the movement of flexion ; 

 2, Inwardly, a condyle with a more extensive curvature than that of the pre- 

 ceding oroove, and, like it, completed by a small anterior glenoid cavity. The 

 carpal surface, moulded exactly on the radial, offers depressions corresponding 

 to the projections on it, and rice versa. 



Mode of union. — The radio-carpal articulation is bound by three ligaments 

 which entirely belong to it ; and by four strong ligaments that are common to 

 it and articulations which will be studied hereafter. 



Of the three Ugamnts proper belonging to the radio-carpal articulation, 

 one forms a thick, rounded funicle, extending from the radius to the fourth 

 bone in an oblique direction downwards and inwards, and concealed by the 

 common posterior ligament. The second (Fig. 130, 5), much smaller, is carried 

 from the supercarpal bone to the external side of the inferior extremity of the 

 radius, and is partly covered by the common external ligament. When the 

 synovial capsule is distended by dropsy, it may form a hernia at the outer side 

 of the carpus, by passing between this small ligament and the common posterior 

 ligament. The third, very delicate, but always present, is deeply situated beneath 

 the last ; it is inserted, for one part, into the radius near the first proper 

 ligament, and for the other, into the second bone and the interosseous ligament 

 which unites the supercarpal to that bone. 



Synovial membrane. — After lining these three ligaments, and the four great 

 ligaments yet to be described, this membrane is prolonged between the three 

 first carpal bones, to cover the superior face of the interosseous ligaments which 

 unite them. It even more frequently descends into the articulation which joins 

 the supercarpal to the first bone ; though it also sometimes happens that this 

 has a particular synovial capsule of its own. 



Articulation of the Two Rows between each other. — Like the pre- 

 ceding, this is an imperfect hinge articulation. 



Articular surfaces. — These are two, and are both transversely elongated, very 

 irregular in their configuration, and divided into three portions. The inferior 

 shows : behind, three small condyles placed side by side ; in front, two slightly 

 concave facets. The superior corresponds to the first by three glenoid cavities 

 and two convex facets. 



31ode of union. — For this articulation, besides the common great ligaments, 

 there are three particular ligammits. Two of these are very short, and are 

 situated behind the carpus, underneath the great common posterior ligament. 

 They are readily perceived by removing the capsular ligament, and strongly 

 flexing the carpus. " The strongest extends vertically from the internal bone of 

 the superior row to the second and third bones of the metacarpal row ; the other 

 descends obliquely from the first bone of the antibrachial row to the second 

 of the inferior row " (Rigot). The third ligament proper, much stronger than 

 the other two, reaches from the supercarpal to the first bone of the inferior row 

 and the head of the external metacarpal bone. It is confoimded, outwardly, 

 with the great external lateral ligament ; inwardly, with the common posterior 

 ligament. Its posterior border gives attachment to the fibrous arch which 

 completes the carpal sheath. This ligament has also a branch which is fixed on 

 the second bone of the upper row (Fig. 130, 4). 



