80 ELEMENTS OF PHYSIOLOGY 



2. Why is it better to have a ball-and-socket joint at the 

 shoulder and a hinge joint at the elbow, rather than vice 

 versa (Fig. 49)? 



3. What economy of motion is there in having the 

 pivot joint in the forearm rather than at the shoulder? 



APPLIED ANATOMY 

 EXERCISE I 



1. What in the composition of a bone gives it stiffness? hardness? 

 toughness? flexibility? 



2. Should chairs and benches have straight backs? 



3. Why is a chair back that is very slanting often injurious? Why 

 is a very deep chair injurious, if deep enough for the front edge to strike 

 the occupant behind the knee? 



4. Why does a young child usually crawl before it walks? 



5. Which girdle is attached directly to the spinal column? Which 

 girdle is attached indirectly? 



6. Why is the arm so often dislocated at the shoulder? 



7. High pillows may cause what deformity? 



8. Which three bones in the body are not attached to other bones? 

 Find twenty-seven bones in the skeleton which are attached to other 

 bones at one end, but have the one end free (Fig. 49) . 



9. Why does a fall not hurt a child as much as it does an adult? 



10. Should a young child be urged to stand or walk? 



11. What part of a long bone is composed of compact tissue? Of 

 very porous tissue ? 



EXERCISE H 



12. Could the neck be broken and death result without breaking 

 a bone? 



13. What would be the result if the ligaments were composed of the 

 yellow fibers of connective tissue instead of the white fibers (Fig. 32) ? 



14. If a child's feet be allowed to dangle from a high seat, what 

 will be the effect? (See 125 ; also Chapter VIII, on Circulation.) 



15. Is the ''straight front" a healthful position? 



1 6. The pivot joint formed by the peg of the axis projecting into the 

 atlas allows the head to rotate through a large part (about half) of a 

 circle. Can it nod in any position in that half-circle ? 



