342 GENERAL ANATOMY. 



they have yielded, either to distention or to pressure; it is 

 particularly when they are compressed that their elasticity is 

 most remarkable. They resist more than the bones and car- 

 tilages, the destructive action of pulsatile tumours. In aneu- 

 risms of the aorta, the vertebrae are worn and destroyed before 

 the fibre-cartilage which separates them. This property is a 

 consequence of their elasticity. The vital properties of the 

 fibro-cartilages are obscure, like those of the ligamentous tissue 

 generally. 



535. In their formation, several of these parts pass through 

 the fibrous state ; others pass directly from the mucous to the 

 fibro-cartilaginous state. It is only accidentally, and in a va- 

 riable manner, that the permanent fibro-cartilages become 

 bony in old age; this, however, occurs more frequently to 

 them than to the ligaments, but less frequently than to the 

 cartilages. 



536. The temporary fibro-cartilages have for use to serve 

 as a type or mould to bones. Those which are permanent, 

 sometimes form flexible, elastic, and very firm bonds, and 

 sometimes serve to facilitate slidings, by the consistency which 

 they give to the surface. 



537. The morbid states of the fibro-cartilages are little 

 known. They unite again after being divided, as is observed 

 after the operation of symphyseotomy. 



Their accidental production is not of very rare occurrence. 

 The centre of an intervertebral ligament may be taken as the 

 type of the species, and as an object of comparison. The ac- 

 cidental fibro-cartilages are, in fact, fibres, like the ligaments, 

 of a milky white like the cartilages, pliant, moist and elastic. 

 According to their form, connexion and uses, the accidental 

 fibro-cartilages may be divided into two kinds. Some are the 

 means of union of certain fractures which have not been con- 

 solidated, either on account of motions, like those of the neck 

 of the femur, the patella and others, or on account of an ex- 

 tensive loss of substance in one of the bones of the fore-arm, 

 leg, metacarpus, skull, &c. places where the fragments can not 

 be brought together. Other fibro-cartilages are formed on the 

 extremity of amputated bones, on the surfaces of supernume- 



