ADJUNCTS OF THE MUSCULAR SYSTEM. 105 



synovial epithelium, are found parts which are formed of 

 resisting fibrous tissue, called articulating ligaments. Out- 

 side the joints again, and around the muscles, are found 

 other fibrous and membraniform apparatus, called aponeu- 

 roses. The object of these two apparatus is not so much, as 

 is generally supposed, to keep the articulating surfaces in 

 contact, as to limit the extent of the movements of the 

 joints. The ligaments which immediately cover the joints 

 act as resistance, with a lever arm which is too short, and 

 would not be able to regulate the movements, were they not 

 aided by the aponeuroses, which are a kind of ligament 

 placed farther off, and, consequently, more powerful. Thus, 

 in the aponeurosis of the thigh, the fascia lata is only a 

 ligamentous bridge thrown from the pelvis to the leg, thus 

 belonging to the coxo-femoral and knee joint; it is intended 

 to prevent too great mobility in the inferior limb. This 

 fascia, though less strong than the articulating ligaments, ex- 

 ercises in this way a much more important influence, because, 

 being placed at a great distance from the centre of motion, 

 it acts with a much longer lever arm. The case is the same 

 with the cervical aponeuroses, which are only ligaments, 

 intended to prevent the too great inclination of the head 

 either backward, or sideways: here, again, these are only 

 membranes, weak in themselves, but which become powerful 

 by the length of their lever arm. 



There exist, however, a certain number of aponeuroses 

 and ligaments, the use of which is evidently not the regula- 

 tion of the movements of the joints : such are the aponeu- 

 roses of investment, which prevent any deviation in the 

 muscles during their contraction. Others, as the annular 

 ligament of the wrist, serve as pulleys of reflexion for the 

 flexor muscles. Others take the place of bones for the inser- 

 tion of the muscles : such are the interosseous ligaments of 

 the forearm and of the leg, the abdominal linea alba, etc. 

 On the other hand, the sclerotic coat, an essentially fibrous 

 membrane in the eye, is intended to preserve to the eye its 

 spherical form, which form is necessary for the preservation 

 of the optical properties of this organ. In general, the 

 principal use of the fibrous tissue is the part which it plays 

 in reference to the joints. 



The ligaments serve to keep the bones in contact only 

 when they are situated between two bones, as in the case of 

 the symphyses, thus uniting two parts of the skeleton which 



