2 GENERAL SCIENCE 



. 



mouth plays a most important part. Some knowledge of 

 Human Physiology as studied in schools is presupposed in 

 these lessons. 



THE HAND 



The bones of the hand serve as a framework, giving to it 

 both form and strength. The many joints of the hand and 



wrist make possible a great 

 variety of movements, and a 

 wide adaptability in uses. 

 The bones are held together 

 at the joints by ligaments, 

 and the surfaces of bones 

 that move upon each other 

 are covered by cartilage. A 

 study of both cartilage and 

 ligaments can be made from 

 a joint obtained at a meat shop. 

 Motion in the parts of the 

 hand and wrist is accomplished 

 by means of muscles, the "lean 

 meat" of animals. Sometimes 

 the muscles are attached directly 

 to the bones, seeming to grow 

 out of the bone itself. In the 



wrist and hand the movement of cord-like tendons beneath 

 the skin may be seen and felt. The muscles here are at 

 some distance from the bones moved by them, and are 

 connected to the bones by the tendons. 



To cause these muscles to act, moving the hand and fingers 

 or holding them at rest as a person desires, the muscles are 

 provided with nerves. In the skin of the inner part of the 

 hand and fingers the terminal fibres of the nerves are so 

 close that the hand through care and training may acquire a 



FIG. i. Bones of the right fore- 

 arm, a, palm; b, back of hand; r,r', 

 radius; u, u f , ulna. 



