THE MUSCULAR SYSTEM. 



•i\:> 



§ 



80. 



The sineivs,tendo)is, are brilliant, white or yellowish structures, 

 composed almost entirely of connective tissue. They are sub- 

 divided according to their figure into the rounded, cord-like, 

 (rue ten <lons, and into membranous aponeuroses {centrum 

 tendineum, galea, tendons of the abdominal muscles, latissimus 

 dorsi, cucullaris, &c.) The two forms, either in their external 

 configuration, or internal constitution, do not admit of definite 

 distinction ; they consist of connective tissue, which is charac- 

 terised by the jjarallelism of its elementary fibres, its consistence, 

 and its poverty in elastic filaments. The elements of the 

 connective tissue, the fibrillce, may be readily perceived, in fresh 

 tendon, to be, as they are everywhere, extremely minute. In 

 the cord-like tendons, they are slightly wavy in their course, 

 all perfectly uniform in size, parallel to the long axis of the 

 tendon, and in the recent state so closely approximated, that 

 the demonstration of the existence of primitive fasciculi is not 

 easy. Such fasciculi, however, do exist, having a breadth of 



many branches, each of which, either tapers off to a conical extremity, or divides into 

 a number of delicate pointed pro- 

 cesses. In either case, the ends of 

 the muscular fibre gradually or sud- 

 denly lose their striation, and pass 

 directly into the irregular nucleated 

 bands of the connective tissue. No 

 sarcolemma can be demonstrated in 

 the branched ends of the muscles, 

 and the bands of the connective tis- 

 sue are directly continuous with the 

 matrix of the muscle; the change, 

 from the one to the other, being 

 evidenced merely by the appearance 

 of the sarcous elements. Nothing 

 can afford a more complete proof of 

 the homology between the pseuuo- 

 fibrillated tissue of muscle and that 

 of connective tissue, than what we 

 find here. — Eds.] 



Fig. 94 A. Branched muscular fibres from the upper lip of the Rat : a, epidermis 

 and aperture of a sebaceous gland ; b, muscular fasciculi dividing at their extremities, 

 the ultimate divisions becoming continuous with the irregular, more or less stellate 

 bands of the subcutaneous areolated connective tissue ; c, " nuclei" of the latter. 



