GENERAL CONSIDERATIONS ON THE STRIPED MUSCLES. 183 



levers, at least at the commencement of their action ; another circumstance 

 which again diminishes their energy. 



APPENDAGES OP THE MUSCLES. 



These are: 1, The enveloping or contentive aponeuroses ; 2, The 

 serous or mucous bursse ; 3, The tendinous and synovial sheaths. 



A. CONTENTIVE APONEUKOSES. These are layers of white fibrous tissue, 

 which envelop, in common, all the muscles of one or several adjoining 

 regions, principally those of the inferior rays of the limbs, where they con- 

 stitute a kind of hollow cylinder. 



These aponeuroses are formed by very resisting interwoven fibres, which 

 are attached to the bones at numerous .points. At their periphery they 

 receive the insertion of one or several muscles, which keep them more or less 

 tense. Their external face responds to a thin fibro-cellular layer that 

 separates them from the skin. The internal face sends lamellar prolong- 

 ations between the muscles, which are destined to isolate these organs in 

 special sheaths. 



The aponeuroses maintain the muscles in their position, and sustain 

 them during their contraction. 



B. SEROUS BURS.Z. The serous or mucous bursse are small cavities, filled 

 with a serous fluid, which are met with at those points where the muscles 

 glide over resisting surfaces. They are generally orbicular or rounded, and 

 their interior is often divided by fibrous bands. 



Their walls are formed by slightly condensed conjunctival tissue, and 

 may be lined by a pavement epithelium ; in which case it is believed that 

 the serous bursa is produced by the simple dilatation of one of the con- 

 junctival meshes. 



C. TENDINOUS SHEATHS AND SYNOVIAL MEMBRANES. Tendinous sheaths 

 is the name given to the half-bony, half-fibrous, sometimes exclusively fibrous, 

 gliding grooves into which the tendons pass when they are inflected to change 

 their direction. 



The tendinous synovial membranes are serous membranes lining the ten- 

 dinous sheaths and covering the tendons at the points where these two parts 

 correspond. They secrete a synovial fluid quite like that of the articulations. 



When they almost completely envelop the tendon, and are afterwards 

 carried to the walls of the sheath, they are termed vaginal. 



Their walls are composed of : 1, A very fine conjunctival membrane, con- 

 founded by its external face with the tendinous sheath, by the other face with 

 the tendon ; 2, A simple layer composed of pavement epithelium, extended 

 over the whole or a part of the internal face of the conjunctival membrane. 



MANNER OF STUDYING THE MUSCLES. 



A. CLASSIFICATION. To facilitate the study of the muscles, two methods 

 may be employed in grouping them. The first consists in classifying them 

 according to their uses ; describing, for example, all the flexors, extensors, etc., 

 of the same region. In the second method, the uses of the muscles are not 

 taken into account, their relations only being considered; and they are 

 divided into groups or regions, which comprise all the muscles situated 

 around a bony ray. The latter is the method now adopted, because it is 

 the most convenient, useful, and rational. 



(Leyh describes the muscles by layers, or according to their situation, 



