354 GENERAL ANATOMY. 



562. The costal cartilages, when denuded, do not produce 

 granulations, but are covered by those of the neighbouring 

 parts. When broken, they do not unite by a cartilaginous 

 substance, but a cellular lamina is produced between them, 

 and the broken place is enveloped with a bony ring furnished 

 by the perichondrium, and which is more or less regular, ac- 

 cording as the fragments have remained more or less exactly 

 in opposition. I have sometimes seen in man, and repeatedly 

 in the horse, the fractures of ossified asternal cartilages, united 

 by a bony callus. 



The costal cartilages are subject to some vices of original 

 conformation, and are even liable to be wanting in whole or 

 in part. In the latter case, it is always the extremity next to 

 the rib that exists. When the thorax is deformed, when it is 

 contracted, as sometimes happens after the cure of pleurisy, 

 the cartilages of the affected side bend and become deformed. 



563. The nasal cartilage, that of the auditory canal, and 

 that of the Eustachian tube, are in a manner articulated with 

 the bones. Those of the larynx, on the contrary, are only 

 attached to the bones by ligaments, and are connected together 

 by moveable articulations. 



These cartilages have still a certain thickness. When their 

 perichondrium is raised, their surface is found to be smooth 

 and compact. Long continued maceration divides these carti- 

 lages into soft and short fibres or filaments. Decoction and mi- 

 neral acids produce the same effects. 



These cartilages are flexible and elastic. By their solidity 

 they preserve the form and cavity of the organs which they 

 contribute to form. Those of the larynx present the remark- 

 able peculiarity of a very rapid growth at the period of puber- 

 ty. These same cartilages sometimes ossify from the adult 

 age, at least in part. Chronic inflammation of the mucous 

 membrane of the larynx, and its ulceration, greatly hasten 

 this ossification, which, in fact, always takes place in phthisis 

 laryngea,and is of frequent occurrence in phthisis pulmonalis. 



When the thyroid and cricoid cartilages are divided, they 

 unite by bony laminae of the perichondrium, which are thicker 

 at the exterior than at the interior of the larynx. 



