410 ANATOMY FOR NURSES [Chap. XX 



Through it precision of effort is rendered possible ; for by it we 

 learn to adjust the force exerted to the weight of the object to 

 be lifted. Thus the function of muscular sense is to enable us 

 to estimate weight or resistance. It also aids in preserving 

 equilibrium and in coordinating muscular action. 



Fatigue. — Prolonged or extreme muscular exercise results in 

 the loss of nutrient material and the accumulation of waste prod- 

 ucts in the muscles. These chemical changes alter the stimula- 

 tion of the nerves connected with muscular sense, and the sensa- 

 tion of fatigue results. 



Visceral sensations. — Sensations which give rise to the feeling 

 of well-being or the reverse, also to the acts of vomiting, coughing, 

 defecation, or urination, are caused by stimulation of the sensory 

 nerves contained in the part of the body immediately concerned 

 in the state or act in question. 



The sense of pressure or touch. — The nerves connected with 

 the sense of pressure or touch are distributed over the entire sur- 

 face of the body, being more or less numerous in all parts of the true 

 skin and the adjoining mucous membrane. They end in two 

 ways: (1) in a ring surrounding a hair follicle, so that pressure 

 exerted upon the hair stimulates these end organs, and (2) in 

 parts of the body where there are no hair follicles, in the tactile or 

 Meissner corpuscles, which are also stimulated by pressure. The 

 distribution of these nerves is not uniform. They are abundant 

 and the pressure points are very close together on the lips and the 

 tip of the tongue, also in parts of the hands and feet in which a 

 delicate sense of pressure is present. 



The temperature sense. — In addition to the end organs of the 

 sense of touch, there are also structures in the skin which are only 

 stimulated by changes in temperature. These structures are of 

 two kinds : hot and cold spots, stimulation of one causing the feel- 

 ing of heat ; stimulation of the other, the feeling of cold. 



In addition to heat and cold these end organs are stimulated by 

 other substances, i.e. menthol stimulates the cold spots and gives 

 rise to a sensation £)f cold, carbon dioxide stimulates the warm 

 spots and gives rise to a sensation of heat, while certain mechanical 

 and electrical stimuli will cause a sensation of cold on a cold spot 

 and of heat upon a warm spot. 



The hot and cold spots and the pressure points can be located 



