CHAP. III.] 



CARTILAGE. 



19 



ground glass : both these conditions are found in what is called 

 ^ true " or hyaline cartilage, and which is the most typical form 

 of the tissue. There is another 

 variety of cartilage in which the 

 intercellular substance is every- 

 where pervaded with fibres. 

 When the fibres are of the white 

 variety, it is called white fibro- 

 cartilaye; when they are elastic 

 fibres, it is called yellow or elastic 

 fibro-cartilage. 



Although cartilage can be read- 

 ily cut with a sharp knife, it is 

 nevertheless of very firm consist- 

 ence, but at the same time highly 

 elastic, so that it readily yields 

 to extension or pressure, and im- 

 mediately recovers its original 

 shape when the constraining 

 force is withdrawn. By reason 

 of these mechanical properties it 

 serves important purposes in the 

 construction of some parts of the 

 body. 



Hyaline cartilage occurs principally in two situations ; viz. 

 covering the ends of the bones in the joints, where it is known 

 as articular cartilage, and forming the rib cartilages, where it is 

 known as costal cartilage. In both these situations the carti- 

 lages are in immediate connection with bone, and may be said 

 to form part of the skeleton. The articular cartilages, in cov- 

 ering the ends or surfaces of bones in the joints, provide these 

 harder parts with a thick, springy coating, which breaks the 

 force of concussion, and gives ease to the motion of the joint. 

 The costal cartilages, in forming a considerable part of the 

 solid framework of the thorax or chest, impart elasticity to its 

 walls. Hyaline cartilage also enters into the formation of the 

 nose, ear, larynx, and windpipe. It strengthens the substance 

 of these parts without making them unduly rigid, maintains 

 their shape, keeps open the passages through them where such 

 exist, and gives attachment to moving muscles and connecting 

 ligaments. 



\ 



J'.RKXAUDOT E.SALLE 



FIG. 13. ARTICULAR HYALINE 

 CARTILAGE FROM THE FEMUR OF AN 

 Ox. s, intercellular substance; p, 

 protoplasmic cell ; n, nucleus. (Ran- 



