MUSCLE TONE 123 



duced by the slight stretching of their attachments, as though the 

 bones had outgrown them a very little. The tension is in itself 

 a stimulus, and is increased by what is called normal muscle 

 tone. 



Slight contractions of fibers are continually going on, caused 

 by various delicate stimuli so delicate that we are not always 

 conscious of them although the muscle is; these contractions 

 constitute muscle tone (tonus) which is important in several ways. 

 First, it holds the muscles ready for instant action, making labor 

 easier; second, it maintains a steady, although slight, production 

 of body heat; third, it assists the steady flow of circulating fluids 

 blood and lymph; and fourth, it maintains favorable conditions 

 in internal organs for the processes of secretion and excretion. 



Although unconscious of normal muscle tone, we can often 

 recognize the increase of tone. One example is the effect of 

 cold; shivering is an instance of exaggerated muscle tone (it is 

 however somewhat complex). Again, some emotions as fear, 

 anger, joy, sorrow, surprise, etc., always increase muscle tone. The 

 expression "all strung up" is in a sense accurate, if not elegant. 

 Also, an attitude of sustained attention produces the same effect 

 and is often prolonged to the verge of conscious fatigue. Some 

 idea of the degree of energy exerted in maintaining increased tone 

 may be derived from the feeling of languor which follows it; 

 people often speak of feeling the "relaxation" after excitement. 



In all of these conditions, the heart is quickened more or 

 less; and, in short, whatever cause, mental or physical, increases 

 the rapidity of the circulation, will contribute to an increase of 

 muscle tone, by preserving nutrition and removing waste matters. 



Diminished tone is the result of overuse or of poor nutrition 

 either of nerve or of muscle, or both- the effect being a tired 

 feeling, or manifesting itself in various ways, such as inability 

 to work, physical and mental inefficiency, etc. The need of a 

 "tonic," or to be "toned up," is a common complaint. 



Rest is necessary for the restoration of muscle tissue after work, 

 in the ordinary activities of life, and still more after excessive 

 exercise, in order that the renewal of muscle plasma may 

 be accomplished and a store of material laid up for further 

 use. This cannot be brought about while the muscle is doing 

 visible work. 



