34 



HUMAN BIOLOGY 



splint bone], 8 wrist bones [7 ankle bones], 5 palm bones 

 [5 bones of instep], 14 finger bones [14 toe bones]. The 

 shin bone is the larger bone between knee and ankle. 



The long, slender splint bone and the 

 shin bone are bound side by side. 



Differences between Arm and Leg. 

 There is a saucer-like bone, called the 

 kneecap, embedded in the large liga- 

 ment which passes over each knee. 

 There is no such bone in the elbow. 

 There is one less bone in the ankle 

 than in the wrist, hence there are the 

 same number of bones in the arm and 

 leg. The shoulder joint is more freely 

 movable than the hip joint. The fin- 

 gers are longer and more movable than 

 the toes; the thumb moves far more 

 freely than the big toe. The instep is 

 much stronger than the palm ; for each 

 instep must support, unaided, the 

 weight of the whole body at each step, 

 with any other weight that the person 

 may be carrying. The palm is nearly 

 flat, but the instep is arched to prevent 

 jars. When the weight of the body is 

 thrown on the foot at each step, the top of the arch is 

 pressed downward, making the foot longer than before. 

 The arch springs up when the weight is removed (Exp. i). 



ILLUSTRATED STUDY. The Shapes of Bones. Write Z,, F, or 1 

 after these names (see Fig. 28, etc.). according as the bones are long, 

 flat, or irregular : face, cranium, vertebra, hip, rib, 

 bone, collar bone, shoulder blade, upper arm bone, 

 arm bones, wrist, palm, fingers, thigh bone, 

 splint bone, ankle, instep, toes, kneecap. 



FIG. 34. BONES OF 

 ARM AND LEG. 



breast- 

 lower 

 shin bone. 



