AND PHYSIOLOGY. 



Ill 



Fig. 128. 



A Doubly Penniform Muscle. 



the Penniform the fibres are short and arranged upon a long 

 tendinous line, like the plumes upon the quill of a feather. 

 The circular form, called Sphincter, is found in parts of the 

 b >dy where the fibres are circular, surrounding some orifice 

 which they partially or entirely close up by their contraction. 

 An example of this is seen around the eye and mouth. A 

 few muscles resemble in structure a ribbon. Others a cord, 

 and others are very thin and expanded, so that they resemble 

 a membrane. All these forms are thus arranged to secure 

 the greatest amount of power with dispatch, and also the most 

 perfect freedom of motion, as well as to adapt themselves to 

 the amount of space furnished them on the skeleton. 



233. Number of Muscles, Single Muscles —The number 

 of muscles in man is 540, being more than twice the number 

 of the bones. They are nearly all arranged in pairs ; that is, 

 both sides of the body have similar muscles, while the single 

 or unmated muscles are only thirteen. Each muscle is pro- 

 vided with one or more antagonist muscles, or those which 

 produce motion in an opposite direction, save a very few sur- 

 face muscles about the head and neck, where the elasticity of 

 the integuments produces the antagonistic motion. 



234. Fascia. — Every muscle is covered by a firm and 

 slightly elastic membrane called Fascia, which serves the 

 double purpose of keeping the fibres firmly in their place, and 

 also of producing a tonic pressure, which gives increased 

 strength to the muscle. An illustration of the utility of this 

 pressure is seen in the fact, that the school-boy, when engaged 

 in running as rapidly as possible in his sports, ties a handker- 



Describe the Penniform and Circular Muscles. Are there any other forms of muscles? 

 Why are muscles of these different shapes ? 233. What is the number of human muscles ? 

 How does this compare with the number of the bones? How many unmated muscles 

 are there ? What is meant by antagonist muscles ? 234. What is the Fascia, and what 

 purpose does it serve ? What illustration of its use ? 



