THE VERTEBRATE BODY 



137 



stages of higher forms the muscular layer is composed of segments 

 known as myotomes. But in the adult stage of the latter this 

 evidence of Vertebrate segmentation largely disappears, since the 

 muscular tissue for the most part assumes the form of highly 



BICEPS 

 BRACHII 



TRICEPS 

 BRACHII y/i 



.EXTENSORS 



Fig. 99. - - Muscles of Man. (Courtesy William Wood and Co.) 



complex longitudinal bands, extensions from which pass into the 

 paired appendages. (Figs. 94, 95.) 



Muscles, such as those attached to the bones, in which contrac- 

 tion can be brought about at will, are termed voluntary muscles, 

 while those which cause most of the movements of the viscera are 



