The Muscles 



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under a very powerful microscope, it will sometimes be 

 seen to consist of a great number of still more minute 

 fibers, called fibrillae. These fibers are also seen marked 

 crosswise with dark stripes and can be separated at each 

 stripe into disks. These cross-markings account for the 

 name striped, or striated, muscle. 



The fibrillae, then, are bound together 

 in a bundle to form a fiber, which is 

 enveloped in its own sheath, the sar- 

 colemma. These fibers, in turn, are 

 further bound together to form larger 

 bundles, called fasciculi, and these, too, 

 are enclosed in a sheath of connective 

 tissue. The muscle itself is made up 

 of a number of these fasciculi bound 

 together by an external wrapping (peri- 

 mysium) of connective tissue. 



76. Structure of the Unstriated Muscle. 



_,, , . , f ., , , , A, muscular fiber, show- 



These muscles consist of ribbon-shaped ing stripes; ^ an d^ 

 bands which surround hollow, fleshy nuclei. (Highly mag- 

 tubes or cavities. As they are never 

 attached to bony levers, they have no need of tendons. 

 The microscope shows that these muscles consist not of 

 fibers, but of long, spindle-shaped cells, united to form 

 sheets or bands. They have no sarcolemma, stripes, or 

 cross-markings like those of the striped muscles. Hence 

 their name of unstriated, or unstriped, and smooth muscles. 



Experiment 17. To show the gross structure of muscle. Take 

 a small portion of a large muscle, as a strip of lean corned beef. 

 Have it boiled until its fibers can be easily separated. Pick the 

 bundles and fibers apart until they are so fine as to be almost 

 invisible to the naked eye. Continue the experiment with the help 

 of a hand magnifying glass or a microscope. 



FIG. 30. 



