122 



HITCHCOCK'S AXATOMY 



both sides (upper and lower) of the finger and be firmly 

 enough secured to the finger to keep them in place, without 

 making the finger of an unwieldy bulk, and at the same time 

 allow the force to be applied upon the center of the finger 

 rather than upon one side ? The answer is this : the muscle 

 which sends its tendons to the second phalanx lies above the 

 other set of tendons, and where the superior tendons join the 

 second phalanx, they are each split into two parts, through 

 which the tendons of the lower muscle pass to the last pha- 

 lanx, and move freely without interruption from the superior 

 muscle or tendons. This arrangement is found in the foot, 

 as well as in the hand, for giving the same motion to the 

 toes, and very much resembles the movement of a cord 

 through a loop. 



246. Muscles of the Thumb and Little Finger— The 

 thumb and little finger, as already mentioned, are supplied 

 with separate muscles in the body of the hand, mainly for the 

 purpose of giving motion from side to side, as well as a partial 

 rotation. In addition to this, there are several muscles upon 

 the fore-arm which give their tendons only to these two ex- 

 tremities. The obvioua use of this arrangement is to give 

 strength and great variety of motion so necessary in the 

 thumb and little finger. 



247. Muscles of the Back, Dorsal Muscle. — Upon the 

 back are found at least thirty pairs of muscles, which are ar- 

 ranged in six layers. These are of various forms and sizes, 

 with complicated and obscure attachments. The main use of 

 these muscles, taken as a group, is to keep the trunk in an 

 upright position, and give a firm attachment for muscles to 

 move the extremities. The outermost layer is very super- 

 ficial, lying directly under the skin, while the deepest layer 

 is deeply imbedded between different processes of the vertebrae. 



Why must one tendon pnss through another rather than pass along by its side? 

 Dowe find this arrangement upon both hands and feet? 246. Which two extremities 

 of the hand have the most muscles given to them? 247. How many pairs of muscles 

 upon the back of the body ? Give the number of layers into which they may be dis- 

 •eoted. State the essential purpose of them. 



