272 ANATOMICAL TECHNOLOGY. 



704. The Obvious Structure of Muscle. A muscle is readily 

 seen to be a collection of more or less elongated, reddish, fleshy 

 bundles attached at each end more or less independently or by a 

 common fibrous structure, the tendon. The bundles are easily sep- 

 arable into smaller bundles called fasciculi. A perimysium or 

 sheath of connective tissue surrounds each muscle, and from this 

 partitions extend between the fasciculi, furnishing each with a sep- 

 arate sheath. 



705. Microscopic Structure. Fibers. Each fasciculus is 

 composed of a variable number of cylindrical fibers. 



Striation. The fibers appear to be composed of alternate light 

 and dark segments. A muscle which has been hardened, in alcohol 

 for example, also presents an appearance of longitudinal striation, 

 and if it be teased carefully, it may be divided into finer threads 

 called fibrilltt; each fibrilla shows the same alternating light and 

 dark bands as the entire fiber. 



Sarcolemma. Surrounding each fiber is a delicate sheath of 

 elastic tissue. 



Nuclei or Muscle Corpuscles. These are clear oval bodies found 

 in the fibers. In Mammalian muscles they lie on the surface of the 

 sarcolemma, but in Amphibia they are distributed throughout the 

 substance of the fibers. 



Length. The average length of a fiber is nearly 3 cm. They 

 are of nearly uniform size throughout, but sometimes branched as 

 in the tongue. 



Connection with Tendons. A. When continued in a direct line 

 with a tendon, the fiber merges into the tendon somewhat abruptly, 

 yet it can be distinguished from tendon only by the absence of 

 cross striation in the latter. 



B. When the fibers join the tendon at a more or less acute angle, 

 they terminate in rounded ends which are received into correspond- 

 ing depressions in the tendinous structures. Quain, A, II, 115. 



