METACARPO-PHALANGEAL ARTICULATION. 



141 



jbf sesamoids. The ligaments may be divided into those proper 

 to the joint and the accessory. The former consist of a capsular 

 and two lateral ones. The capsular ligament passes from the 

 lower end of the large metacarpal bone to the head of the os 

 suffraginis, and is attached to the lateral liga- 

 ments, which stretch from the infero-lateral 

 aspect of the metacarpus to the supero-lateral 

 surface of the os suffraginis. 



The accessory ligaments are those imme- 

 diately connected with the sesamoid bones. 



The superior sesamoidean or suspensory 

 ligament is a long, strong band, 

 arising posteriorly from the lower 

 bones of the carpus and the head 

 of the metacarpus, occupying the 

 space between the splints. It 

 bifurcates, and becomes attached 

 to the summits of the sesamoids, 

 whence the parts pass downwards 

 and forwards, reuniting as the 

 broad ligament, and joining the 

 extensor pedis tendon at the 

 antero-inferior part of the os 

 suffraginis. 



Th^inferior sesamoidean liga- 

 ments are named the external or 

 long, the middle or short, and 

 the internal or crucial. The 

 external one is Y-shaped, and 

 runs from the base of the sesamoids to the 

 supero-posterior part of the os coronae. The 

 middle one is V-shaped, arising from the base 

 of the sesamoids, and it passes down to a 

 ridge on the back of the os suffraginis. The 

 internal one, crucial or X-shaped, likewise 

 passes from the base of the sesamoids to the 

 supero-posterior part of the os suffraginis, its fibres intercrossinp. 

 The lateral sesamoidean ligaments, external and internal, are 

 two thin layers, passing from the external surfaces of the sesa- 

 moids to the tubercles on the head of the os suffraginis. Pos- 

 teriorly, the sesamoid bones are connected by the interosseous 



Fig. 56. 

 Sesamoidean and digi- 

 tal ligaments— posterior 

 aspect, a, Suspensory 

 ligament; 6 6 6, External 

 and middle inferior sesa- 

 moidean ligaments. The 

 central bundle is the Y, 

 the two lateral ones 

 forming the V ligament; 

 c, Annular sesamoidean 

 ligament; dd, Posterior 

 ligaments of the pastern 

 joint ; e e. Lateral, and 

 /, Inferior, navicular 

 ligaments. 



Fig. 57. 

 Deep sesamoid, 

 ean ligaments, a, 

 Inter-sesamoidean 

 ligament ; 6, Cru- 

 cial or X liga- 

 ment. 



