CHAPTER VI. 



MUSCULAR TISSUE : STRIATED OR STRIPED ; NON-STRIATED OR 

 PLAIN; ATTACHMENT OF MUSCLES TO SKELETON; PROMI- 

 NENT MUSCLES OF HEAD AND TRUNK ; PROMINENT MUSCLES 

 OF LIMBS. 



Muscular tissue is the tissue by means of which the active 

 movements of the body are produced. It is a more specialized 

 kind of tissue than the connective, which, as we have seen, is 

 used chiefly for mechanical purposes. Muscular tissue is irri- 

 table, and if we irritate or stimulate it, it will respond. We 

 may irritate or stimulate the bones, ligaments, or other connec- 

 tive tissue structures and they will not 

 respond, they will remain immovable ; if, 

 however, we stimulate muscular tissue, 

 it will show its response to the stimula- 

 tion by contracting. This power of the 

 muscle to contract is called muscular con- 

 tractility. All muscular tissue consists 

 of fibres, and whenever a muscle fibre con- 

 tracts, it tends to bring its two ends, with 

 whatever may he attached to them^ together. 

 Influences which irritate or stimulate 

 muscle fibres are spoken of under the 

 general name of stimuli. 



Muscle fibres are of two different kinds, 

 and we therefore distinguish two varieties 

 of muscular tissue, the striped or striated, 



and the plain or non-striated. The striated muscle is nearly 

 always under the control of the will, and is often spoken of as 

 voluntary muscle ; the non-striated is usually withdrawn from 

 the control of the will, and is often termed involuntary muscle. 



Voluntary, striated muscle is composed of long slender fibres 

 measuring on an average about -^^ inch (.050 mm.) in diame- 



53 



Fig. 51. — Diagram of 

 Muscle Fibre with Sar- 

 colemma attached. 



