THE SKELETON 



73 



120. THOUGHT LESSON. The Spinal 

 Column. 



1. Observe a single vertebra(Fig. 68). 

 What is the use of the "body "of a ver- 

 tebra? the arch? the processes? 



2. How is the spinal column con- ^ 

 structed so as to allow movement 

 (Fig. 69), without seriously displacing 

 any organ supported by it ? 



3. In the general form of the spinal 

 column what shows that its strength 

 is proportional to the weight to be 

 supported (Fig. 69)? 



4. Do the spinous (or rear processes) 

 project at the same angle in all parts 

 of the spinal column (Fig. 69) ? 



5. Find, by bending your own body, L. 

 or by studying Figure 69, what part 

 allows least motion. Why ? 



6. Why are the spinous processes 

 a source of danger to the spinal cord, 

 instead of a protection ? (Suggestion : 

 a blow from the rear, or a fall upon a 

 process, would cause what part of a 

 vertebra to break ? ) 



7. In what region might a blow 

 from the rear, or a fall, cause the pro- 

 cess to snap off and leave the cord 

 uninjured ? 



8. If the processes inclined in the FIG. 69. The Vertebral 

 neck and the lumbar regions, as in 



the thoracic region, what disadvantage 



WOUld there be ? 



9. Which part of the spinal column 

 is most easily sprained ? Which next ? 



' 



dorsal, or thoracic; L, first 

 lumbar vertebra ; S, sacrum; 



c, Coccyx ; sp , spinous 

 *' transvcr$e 



