ATTACHMENT OF MUSCLE TO BONE. 439 



Fig. 225. lemma, is again raised up. The two 



latter illustrations are from Todd and 

 Bowman. 



Different portions of the length of 

 the fibre assume this condition at dif- 

 ferent moments, and hence the whole 



Fasciculus contacting. structure is thrown into a form which 



recalls the motion of a worm. The zigzag appearance pointed out by 

 Prevost and Dumas arises from the circumstance that when relaxa- 

 tion of the fibre occurs all its parts are not brought at once into the 

 same state, but while some are contracted others are in the opposite con- 

 dition. A muscle, during its contraction, appears to have nearly the 

 same solid dimensions which it had during its relaxation. This has led 

 to the deceptive conclusion that whatever it has lost in length it has 

 gained in thickness. There must, however, be a diminution correspond- 

 ing to the recognized amount of waste, for it is well known that destruc- 

 tion of a portion of its tissue is the essential condition of the activity of 

 a muscle. The various degrees of energy with which the contraction 

 takes place at different times is to be explained not so much by the 

 more or less energetic shortening of the cells as by the varying number 

 of fibres which are simultaneously contracting, or by the different frac- 

 tional portion of each which is going into action at once. As the mus- 

 cular effect is more energetic, so will the sense of fatigue be more speedy, 

 for while one fibre is acting another is resting, and the same remark ap- 

 plies to different parts of even the same fibre. It is to this reciproca- 

 tion of motion that the sound usually emitted while the muscle is in ac- 

 tion, a low ringing sound, is to be attributed. 



Striated muscle is often attached to bone, or other substance on which 

 it has to exert its mechanical power, by intervening fibrous jj usc i e at t a ch 

 tissue constituting tendon. These fibres are collected in ed to bone by 

 groups, so as to present primary, secondary, and tertiary fas- 

 ciculi. The tendinous fibres are brought in relation with the sarcolem- 

 ma, and thus form a sheath connected with adjacent ones by other de- 

 tached fibres. These may be considered as converging from all parts of 

 the muscle to its extremities, and thus giving rise to its tendon. In 

 - 226 - some instances the muscular fibres attach them- 



selves to the side of the tendon, which does not 

 then undergo subdivision. 



From the peculiar structure of muscular tis- 

 sue, .the capillary vessels which are distributed 

 to it must run in a direction for the most part 

 parallel to its fibres, as in Fig. 226. Their 

 Distribution of muscular capillaries. mo <3 e O f branching, transverse and longitudinal, 



