246 MOTION AND COORDINATION 



more, the surface perimysium and that within the muscle 

 are both continuous with the strong, white cords, called 

 tendons, that connect the muscles with the bones. By 

 uniting with the bone at one end and blending with the 

 perimysium and fiber bundles at the other, the tendon 

 forms a very secure attachment for the muscle. The 

 perimysium and the tendon are thus the means through 

 which the fiber cells in any muscle-organ are made to pull 

 together upon the same part of the body (Fig. 1 10). 



Purpose of Striated Muscles. The striated muscles, 

 by their attachments to the bones, supply motion to all the 

 mechanical devices, or machines, located in the skeleton. 

 Through them the body is moved from place to place and 

 all the external organs are supplied with such motion as 

 they require. Because of the attachment of the striated 

 muscles to the skeleton, and their action upon it, they are 

 called skeletal muscles. As most of them are under the 

 control of the will, they are also called voluntary muscles. 

 They are of special value in adapting the body to its sur- 

 roundings. 



Structure of the Non-striated Muscles. The cells of 

 the non-striated muscles differ from those of the striated 

 muscles in being decidedly spindle-shaped and in having 

 but a single well-defined nucleus (Fig. 1 1 1). Furthermore, 

 they have no striations, and their connection with the nerve 

 fibers is less marked. They are also much smaller than the 

 striated cells, being less than one one-hundredth of an inch 

 in length and one three-thousandth of an inch in diameter. 



In the formation of the non-striated muscles, the cells 

 are attached to one another by a kind of muscle cement to 

 form thin sheets or slender bundles. These differ from 

 the striated muscles in several particulars. They are of a 

 pale, whitish color, and they have no tendons. Instead of 



