LIGAMENTS. CARTILAGE. JOINTS 



35 



skeleton of a very young animal consists entirely of cartilage, and 

 as the animal develops into maturity, the bones become gradu- 

 ally harder by the slow absorption of mineral matter derived from 

 its food substances, till at last the skeleton consists almost entirely 

 of bone. 



Cartilage is not supplied with blood, hence it is white or semi- 

 transparent. When boiled for some time with water, it yields a 

 substance called chon- 

 drine (Gr. chondros, 

 cartilage), which closely 

 resembles gelatine, be- 

 ing soluble in hot water 

 and forming a 'jelly' 

 on cooling. 



Those cartilages 

 which are converted 

 into bone duringgrowth 

 are called temporary 

 cartilages; whilst those 

 which remain un- 

 changed are termed 

 permanent cartilages. 



The uses of carti- 

 lage are various. It 

 is tough, flexible, and 

 elastic ; and will be 

 found in all parts of 

 the body where these 

 properties are essential. 

 Sometimes it helps to 

 form a flexible frame- 

 work, as in the costal 

 cartilages of the walls 

 of the chest. The 

 intervertebral carti- 



lages of the backbone Fig. 38, The Ligaments and Cartilages of 

 are flexible pads which the Breast. 



bind the Vertebrae tO- I to I0) l ^ e en c- s f the r 'b s > w ' tn their costal cartilages, and 

 the ligaments uniting these cartilages ; 1 1, cartilaginous 

 end of the sternum ; 12, ligaments uniting the clavicle 

 with the sternum ; 13, ligaments binding the clavicle to 



the first rib _ 



Same 



, 

 , at tue 



timp allnwincr n 



- d.nuwm to a 

 degree of movement, 

 enabling us to bend the back. In aged persons these cartilages 

 become hardened by the absorption of lime, hence the stiffness 

 of the vertebral column. They also act as buffers in deadening 

 the effect of a blow or shock. Another use of cartilage is to 



D 2 



