298 SKELETON.- 



of this ligament belonging to the thumb, and in its thickness, 

 are developed the sesamoid bones. 



The Lateral Ligaments are situated one on each side. They 

 arise from the sides of the metacarpal bone behind the former, 

 and in connexion with it, and, descending obliquely forwards, are 

 fixed into the sides of the upper end of the first phalanx. They 

 are round, distinct, and strong, and are formed from numerous 

 parallel fibres. 



The Synovial Membrane lines this articulation,being displayed 

 over its lateral and anterior ligaments, and on the articular faces 

 of the bones. It is reflected on the metacarpal bone, some little 

 distance from the margin of its cartilage in front, whereby the 

 cavity is enlarged, arid the flexion of the fingers is favoured. It 

 is in contact, behind, with the tendon of the extensor muscle, 

 which there supplies the place of ligament. 



Of the Phalangial Articulations. 



There are two of these to each finger, and one only to the 

 thumb. They are provided with an anterior ligament, a lateral 

 ligament on each side, and a synovial membrane. 



The anterior Ligament corresponds so exactly with what has 

 been said in the preceding article on the same structure, that, 

 with the exception of its being smaller, the description already 

 given, will suffice. It seems to answer, in every respect, the 

 same objects. 



The Lateral Ligaments, also, arising from the sides of the pha- 

 lanx above, run downwards and somewhat forwards to be insert- 

 ed into the upper part of the sides of the phalanx below. 



The Synovial Membrane has reflections corresponding with 

 those of the preceding articulations, with the addition that it co- 

 vers more of the anterior inferior face of the first and second 

 phalanges. Thus, by cutting through the anterior ligament, 

 longitudinally, and turning it aside, it will be seen that the cavity 



