ABTICVLATIONS OF THE ANTERIOR LIMBS. 149 



external lateral ligament and the inferior tendon of the external flexor of 

 the metacarpus ; the others adhere to the capsular ligament. The inter- 

 osseous ligaments are implanted ia the grooves of insertion which separate 

 the diarthrodial facets. One of them, derived from the common superior 

 ligament, unites the first to the second bone. The two others, situated 

 between the three last carpal bones, are confounded with the corresponding 

 anterior ligaments. 



Abtioulations uniting the Caepal Bones of the Second Eow. — • 

 These are arthrodial articulations, like the preceding, but numbering only 

 two. Tliey are fixed by two anterior and two interosseous ligaments. One of 

 the anterior ligaments joins the first bone to the second, and strongly adheres 

 to the capsular ligament ; the other is entirely covered by the lateral internal 

 ligament, and attaches the two last bones to each other. Of the two inter- 

 osseous ligaments, the second alone is confounded with the corresponding 

 anterior ligament. That which is situated between the two first bones is 

 separated from the anterior ligament by one of the diarthrodial facets between 

 these bones. 



Eadio-caepal Abticulation. — The inferior extremity of the radius, in 

 becoming united to the upper row of carpal bones, constitutes a diarthrosis 

 which, from the nature of the movements it permits, may be considered as 

 an imperfect hinge joint. 



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

 irregular, presents -. 1, Outwardly, a wide groove, limited in front by a 

 small glenoid 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 tliat of the 

 preceding groove and, like it, completed by a small anterior glenoid cavity. 

 The carpal surface, moulded exactly on the radial, offers depressions corre- 

 sponding to the projections on it, and vice versa. 



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

 ments 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 ligaments 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. 87. 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 inter^eous ligament which unites the supercarpal 

 to the second bone. W 



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. 



Abticulation of the Two Eows between Each Other. — Like the 

 preceding, this is an imperfect hinge articulation. 

 13 



