CHAPTER VI. 



MUSCULAR TISSUE. 



CERTAIN muscles are under the control of the 

 will, and are called voluntary muscles ; and as these 

 have, as we shall see presently, a very characteristic 

 transverse striation of their structural elements, they 

 are also called striated voluntary muscles. To this 

 class belong, among others, the muscles of locomo- 

 tion and the voluntary muscles of the trunk and 

 head. Other muscles are not under control of the 

 will, and are hence called involuntary. A certain 

 portion of these involuntary muscles possess the 

 same striation of their elements as the voluntary 

 muscles, and hence are called involuntary striated 

 muscles. These are found in the heart. In another 

 kind of involuntary muscles, such as is found in the 

 intestine and bladder, the elements do not possess 

 the same kind of striations, and they are hence called 

 smooth or non-striated involuntary imiscles. 



We have thus to study three kinds of muscles : 



. ( a, smooth or non-striated, 



1. Involuntary muscles \ . 



[ o, stnatedc 



2. Voluntary muscles (striated). 



93 



