62 ANATOMY AND PHYSIOLOGY. 



it and electricity having been long supposed to be modifications of 

 the same agent. 



A very important remark with regard to the muscles is the sacri- 

 fice that we see of power to velocity and beauty of form. The 

 muscles are generally inserted disadvantageously for mechanical 

 power. For instance, the muscles which bend the elbow are 

 inserted into the forearm about one inch beyond the elbow-joint, 

 while the weight which is to be raised in the hand is nearly twelve 

 times further off. Hence twelve times the power is expended in 

 raising the weight from off the table, if the arm is laid flat along it, 

 than if the muscles had been inserted directly into the hand. But 

 what is lost in power is gained in velocity ; the hand moves twelve 

 times faster than the bone near the elbow, and hence the force with 

 which we can strike a sudden blow. A man can cut or break a bar 

 of iron with a stroke of an axe in his hand, while the whole weight 

 of his body, if merely let down upon it, could not even drive a 

 nail. 



It has already been stated that the muscles are thrown into action 

 through the medium of the nerves. Those which are connected by 

 their nerves to the brain, are voluntary muscles ; but there are 

 many, such as the heart, and those for carrying on respiration and 

 for keeping the bowels in motion, which are not dependent on the 

 brain, and consequently not subject to the will ; because if they 

 had been so, and the individual were to forget to keep them going, 

 life would be at once extinguished. There is, therefore, a distinc- 

 tion of muscles into voluntary and involuntary, but the prosecution 

 of this subject belongs to the chapter upon the nerves. 



The tendons of the muscles expand in many places into sheaths, 

 with which all the limbs are covered. These are shining webs of 

 a bluish color, which keep the muscles in their places, and prevent 

 them from starting out. When tendons pass over bones, or through 

 rings, they are generally surrounded by bags of the same nature as 

 the synovial membrane of the joints, which have the effect of en- 

 abling them to glide easily, and without friction. Sometimes these 

 bags enlarge, and form firm round swellings, particularly on the 

 back of the wrist, where they are popularly called "weeping sinews." 

 A popular cure is to wear a shilling or a piece of lead firmly tied 

 over it ; another plan is to have them punctured with a proper 

 needle, when a quantity of jelly is squeezed out, and the cure is 

 generally completed by pressure continued for a few days. 



The muscles are the seat of that dull long-continued pain which 



