276 



ADVANCED PHYSIOLOGY 



Muscle Fibre 



active part of the muscle, the sarcolemma itself having noth- 

 ing to do with its movement. A muscle, therefore, con- 

 sists of thousands of minute 

 fibres, each able to contract, 

 bound together in bundles to 

 form fasciculi. 



Tendons, ligaments, sarcolem- 

 ma, periosteum all belong to 

 the body material called connec- 

 tive tissue. It is always fibrous 

 or membranous in structure, and 

 is so abundant that it has been 

 said that if all other tissues were 

 dissolved away, the shape of the 

 body would still be perfectly 

 preserved. 



Blood Supply to Muscle. Into 

 each muscle enter one or more 

 arteries which divide into minute 

 branches and finally end in a set 

 of capillaries (described in a pre- 

 vious chapter; Fig. 80). In this 

 way each individual muscle fibre 

 is in contact with blood vessels 

 and from them obtains its nour- 

 ishment necessitated by the 

 activity of the muscles. If 

 muscle is soaked in water for 

 while, the blood will filter out and 

 leave the muscle nearly white. 

 Contraction of Striped Muscle. When a muscle contracts 

 the two ends are simply drawn toward one another, while a 

 corresponding swelling occurs at the middle of the fibre. The 

 muscle does not really become any smaller, but merely shorter 

 and larger around; Fig. 140. It is evident from Figure 137 that 



NucIA 



Tendon 



FIG. 139. Two MUSCLE FIBRES 



With tendon fibres attached at their 

 ends. 



