THE MUSCLES 



37 



r> 



FIG. 14 shows the muscles and tendons of the hand ; A showing the palm, B the back of the 

 hand. These numerous muscles and tendons form a very complicated piece of mecha- 

 nism, and help to give to the hand its marvellous dexterity and flexibility. Over certain 

 joints, such as the wrist and ankle, ligaments in broad bands, as seen in Fig. 14, B, C, 

 are bound. They keep the tendons in place. 



vulnerable (Fig. 15). The muscles in the 

 front part of the thigh unite to form a sin- 

 gle and very powerful tendon, and enclose 

 a small bone called the knee-pan, which, 

 acting like a pulley, greatly increases 

 their power, and at the same time protects 

 the front of the knee-joint (Fig. 16). 



9. Muscular Contraction. The muscles, 

 when acted upon by the appropriate stim- 

 ulus, contract, or so change their shape, 

 that their extremities are brought nearer 

 together. The bending of the arm, or of 

 a finger, is effected in this manner, by the 

 will ; but the will is not the only means 

 of producing this effect. Electricity, a 

 sharp blow over a muscle, and other stim- 

 uli, also cause it. Contraction does not 



Fiu. 15 

 LOWER PORTION OP THE LEO 



9. What are the causes of muscular contraction ? 



