INSERTION OF THE MUSCLES. 213 



acted on the bones ? Every muscle is attached by its 

 extremities, generally to the bones, though in a few in- 

 stances one of the .points of attachment may be a soft 

 part. They are supplied with arteries, veins and nerves 

 in greater abundance, than any other organs. The 

 thumb receives more nerves, than is sent to the whole 

 liver. They are fixed to the skeleton, lying in succes- 

 sive layers over one another, though slightly separated 

 by cellular tissue, filling up the general outline of the 

 body, and giving distinctness and character to its forms. 



Emily. Those are muscles swelling under the skin, 

 in the motion of the arms or feet, are they not ? I have 

 often observed them very prominent in paintings and 

 statues. 



Dr. B. More so probably, than you ever did in the 

 human figure. It is an exaggeration which the Italian 

 masters delighted in, and the moderns servilely copy it 

 from them. 



The muscles are the grand organs of locomotion, 

 moving the body from place to place, and giving us 

 power to execute the most delicate operations. This 

 effect they produce by virtue of their contractile power, 

 of which we have already spoken. The contraction of 

 a muscle by shortening the distance between its two ex- 

 tremities, must of course approximate the parts to which 

 they are attached. 



Emily. You observed just now, Dr. B., that the 

 muscles are attached to the bones, and hence I cannot 

 possibly conceive how this approximation can be effected. 

 For if a muscle lie along on a bone through its whole 

 length, with its extremities fixed in the extremities of the 

 bones, how in the name of common sense, can these two 

 ends of the bone be brought nearer together, without 

 bending or breaking the bone. 



Dr. B. I perceive you have one very important fact 

 yet to learn about the relative situation of the bones and 

 muscles, for they are never inserted in the manner you 

 supposed. Recollect that both extremities of the mus- 



