174 THE MUSCLES. 



They arc distinguished as striated (or striped) and non-striated (or 

 unstriped) muscles, according to the character of the anatomical element 

 composing them. 



The non-striated (or unstriped) muscles are removed from the influence of 

 the will, and belong to the organs of vegetative life. They are also 

 designated as internal muscles, or muscles of organic life. 



The striated (or striped) muscles, differ from the first in that, with the 

 exception of the fleshy tissue of the heart, their contractile power is 

 immediately placed under the influence of the will. They are more 

 particularly concerned in the execution of the functions of relation, 

 which causes them to be named the external muscles, or muscles of animal 

 life. These muscles are nearly all attached to the skeleton, and represent 

 the active agents in the movements of the osseous framework ; they will, 

 therefore, be the only ones referred to in this place, in studying the 

 locomotory apparatus. 



But before entering upon the particular description of each muscle, we 

 will allude to the general considerations relative to their history. 



CHAPTER I. 



GENERAL CONSIDERATIONS ON THE STRIATED MUSCLES. 



THE STRIATED MUSCLES IN GENERAL. 



IN this first paragraph, we will survey in a general manner the volume, 

 situation, form, direction, attachments, relations, and names of the muscles 

 belonging to the locomotory apparatus. 



A. VOLUME. Nothing is more variable than the respective volume of 

 the external muscles. What a difference there is, for example, between the 

 small scapulo-humeral muscle and the long vastus or ilio-spinalis (longissimus 

 dorsi) ! and what a number of intermediate sizes between these three points 

 of comparison ! There are consequently very great, great, medium, small, 

 and very small muscles. 



The weight of the total mass of these organs varies according to the 

 species, age, sex, and state of health ; but taking a general average, it will 

 be found that it represents nearly one-half the entire weight of the body. 



B. SITUATION. There is no need to insist upon the fact, that a knowledge 

 of the situation of the muscles is one of the first objects to be acquired with 

 regard to their disposition. 



They may, like the bones, be described in two ways. 



1. In relation to the median plane of the body, from whence their division 

 into pairs and single muscles. The last, very few in number, are far from 

 exhibiting the symmetry which exists in the bones of this division, as may 

 be seen in the diaphragm. 



2. In relation to the other organs, such as the bones and surrounding 

 muscles. 



C. FORM. With regard to their absolute form, the muscles, again, like 

 the bones, are classed as long, wide, and short. 



Long muscles. These muscles are more particularly met with in the 

 limbs. Provided with a principal axis, to which we may ascribe the effect 

 of their contraction, they present a middle portion usually protuberant, and 



