BOOK III. 



PART I. 



CHAPTER I. 



ON THE GENERAL ANATOMY OF THE MUSCLES.* 



THE muscles (musculi) by their contraction produce the va- 

 rious flexions of the body, and are, therefore, the organs of mo- 

 tion. They may be known by their redness, softness, irrita- 

 bility, contractility, and by their being formed of long parallel 

 fibres. The redness, however, does not always attend them ; 

 as this colour is very faint in the foetus, and does not exist at 

 all in animals that have not red blood. They form a very con- 

 siderable share of the whole bulk of the body. 



Though the most perfect organs of motion, and producing it 

 more efficiently and rapidly than any other apparatus, they are 

 not indispensable to it; for they are not observable in animals of 

 a very low grade, which apparently consist of a sort of cellular 

 or mucous substance. In the next grade of animals, as the 

 worms, where there is a deficiency both of bony and of carti- 

 laginous skeleton, the muscles are perceptible, and produce lo- 

 comotion by their attachment to the skin or integuments; and, 

 finally, in animals which have a skeleton, the muscles are al- 

 most exclusively attached to its different points, and by alter- 

 nately approximating them, effect locomotion. 



The muscles of the human body are referrible to two classes, 

 in consequence of their position and functions, though they pre- 



* These organs were very imperfectly known to the ar dents, excepting Ga- 

 lon, and had not generally received names till the time of Sylvius, A. D. 1587. 

 The paramount authority of Albinus, in this department of anatomy, in his work 

 Historia Musculorum Hominis, Leydcn, 1734, has induced me to adopt it as the 

 standard of correct description and nomenclature, with but few exceptions. 



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