90 OF THE APPENDAGES TO BONE. 



strength ; the loss of elasticity thus occasioned is, however, 

 amply made up by the formation of the hock. 



SECTION VIII. 



OF THE APPENDAGES TO BONE. 



The appendages to bone consist of cartilages, periosteum, 

 medulla, ligaments, and synovia. 



Cartilages may be divided into four kinds : articular, inter- 

 articular, non-articular, and temporary. Considered gene- 

 rally, cartilage (familiarly called gristle) is a smooth, minutely 

 fibrous, white, elastic substance ; less hard than bone ; 

 and when in health having no vascularity. 



Articular cartilages furnish the extremity of every bone in 

 which there is much motion ; being in form of a layer, which 

 is thickest at the point of extreme pressure. By these 

 means the bones slide easil}?^ on one another ; and the elas- 

 ticity of the interposed cartilage prevents the effects of that 

 concussion which must otherwise take place between two 

 such inelastic bodies as bones, being driven forcibly to- 

 gether. 



The non-articular cartilages may be divided into the at- 

 tached and unattached. Attached cartilages are such as are 

 placed on the ends of bones not articulated ; as the point of 

 the hip ; sides of the foot ; edges of the orbits, &c. They 

 are likewise interposed between bones immoveably joined 

 together. The cartilages of the ribs are of this kind ; and 

 afford flexibility to parts that would otherwise have but 

 little. The division of the nostrils is an attached cartilage ; 

 serving the purpose of bone. The unattached cartilages 

 serve to sustain parts without adhering to any bone ; those 

 of the ears and larynx are familiar instances, A variety 

 exists, which may be named fibro-cartilaginous, from its 

 partaking of the properties of both cartilage and ligament ; 

 such are those between the splent bones, &c. The tem- 

 porary cartilages are those of which the ends of bones are 

 formed in young animals ; they become very vascular ; that 

 they may be the more easily converted into bone as the 

 other organs become fully ossified. There are but six 



