THE PROPERTIES OF MUSCLE TISSUE 121 



arteries and small branches, are in intimate relation 

 with the fibers, the smaller branches running parallel 

 to the muscle bundles and sometimes lying within 

 them. The nerves are derived from the sympathetic 

 and cerebrospinal systems; sympathetic ganglion are 

 also present. 



The Physiological Properties of Muscle Tissue. 

 Consistency. The consistency of muscle during life 

 depends upon the activity of the part upon which the 

 muscle is acting. Relaxed muscles are soft and fluc- 

 tuating; when touched under tension or doing work 

 the muscles are hard and resistant. The degree of 

 tension of course depends upon the size of the muscle 

 and the amount of work required. 



Cohesion. Cohesion of muscle depends upon the 

 amount of connective tissue it contains; and it is this 

 which enables it to resist the forces of traction and 

 pressure. 



Elasticity. Muscle possesses great elasticity, or the 

 power to stretch beyond its normal length through 

 the action of external forces, and of resuming the 

 normal length when those forces are removed. The 

 degree of elasticity of muscle during life depends 

 upon the proper amount of nourishment, exercise, 

 healthy condition of blood, unimpaired nerve supply, 

 and absence of any pathologic or diseased condition. 

 Should any of these conditions interfere, the elasticity 

 would be impaired. 



Tonicity. This is the tension or tonus of the muscle 

 and is a property which is essential to counteract 

 the stretching of a muscle and then to return and 

 maintain it in a normal state, ready to be acted upon 

 by the ensuing contractions. 



Irritability and Contractility. All muscles when 

 irritated by a stimulus will respond by a change of 

 shape, becoming shorter and thicker called muscular 

 contraction, and on withdrawing the stimulus the muscle 

 will resume its normal shape and position. 



