26 



THE FRAMEWORK OF THE BODY 



14. The abundant supply of inter-vertebral cartilage adds 

 greatly to the elasticity of the frame. It is due, in part, to 

 this elastic material that the brain and other delicate organs 

 are not more frequently injured by the shock of sudden 

 falls or missteps. During the day, the 

 constant pressure upon these joints, 

 while the body is erect, diminishes the 

 thickness of the cartilages; so that a 

 person is not so tall in the evening as 

 in the morning. The effects of this 

 compression pass away when the body 

 is in a reclining posture. (Read Note 3.) 

 15. Cartilage, or "gristle," consists 

 of round or oval cells, imbedded in a 

 matrix, or base, which varies in the 

 three forms of cartilage found in the 

 human body. These three are, 1, hya- 

 line) 2j white Jibro-cartilage, and 3, yellow 

 Jibro-cartilage. 



Hyaline cartilage is that found on the 

 articular ends of bone, and the cartilages 

 of the nose and larynx. That covering 

 the articular ends of bones serves for 

 the purpose of forming bone, the long 

 bones receiving their chief growth from 

 the cartilages covering both ends. 



White Jibro-cartilage is found, among 

 other places, in the disks between the 

 vertebrae. It differs from hyaline car- 

 tilage chiefly in its matrix, which is 

 more fibrous in character. 



Yellow Jibro-cartilage differs from the 

 white again chiefly in the structure of 

 its matrix, whose fibres are found in greater number and 

 density. The best example of it is found in the external ear. 



3. Some Causes of Curvature of the Spine. " Much as horse-riding 

 is valued on account of the healthful character of its exercise, yet an over- 

 indulgence by young ladies owing to the oblique position in' which the 



14. Ya.lue of inter-vertebral cartilage? Structure? 10. Wtyit three fonps of cartilage ? 



Sacrum, 



Os Coccygis 



FIG. 10. THE SPINAL 

 COLUMN 



