54 



HANDBOOK OF PHYSIOLOGY. 



form an intricate interlacement about the cells, and in their general 

 characters are allied to the yellow variety of fibrous tissue : a small and 

 variable quantity of hyaline intercellular substance is also usually present. 



A variety of elastic cartilage, sometimes called cellular, is found to 

 form the framework of the external ears of rats, mice, or other small 

 mammals. It is composed, as its name implies, almost entirely of cells 

 which are packed very closely with little or no matrix. When present 

 the matrix consists of very fine fibres which twine about the cells in 

 various directions and inclose them in a kind of network. Elastic car- 

 tilage seldom or never ossifies. 



3. White Fibro-Cartilage. 



Distribution. White fibro-cartilage is found to occur: 



1. As inter-articular fibro-cartilage, e.g., the semilunar cartilages of 

 the knee-joint. 



2. As circumferential or marginal cartilage, as on the edges of the 

 acetabulum and glenoid cavity. 



3. As connecting cartilage, e.g., the inter-vertebral fibro-cartilages. 



4. In the sheaths of tendons and some- 



r- f ijj: times in their substance. In the latter situ- 



ation the nodule of fibro-cartilage is called a 

 sesamoid fibro-cartilage, of which a specimen 



i 



Cells of 

 cartilage. 



Very fibrous 

 matrix. 





Fig. 57. 



Fig. 58. 



iiiiiljiiiliiiiillli 



Fig. 57. White fibro-cartilage. (Cadiat.) 



Fig. 58. White fibro-cartilage from an inter-vertebral ligament. (Klein and Noble Smith.) 



may be found in the tendon of the tibialis posticus in the sole of the foot, 

 and usually in the neighboring tendon of the peroneus longus. 



Structure. White fibro-cartilage (fig. 58), which is much more widely 

 distributed throughout the body than the foregoing kind, is composed, 

 like it, of cells and a matrix; the latter, however, being made up almost 

 entirely of fibres closely resembling those of white fibrous tissue. 



In this kind of fibro-cartilage it is not unusual to find a great part 

 of its mass composed almost exclusively of fibres, and deriving the name 



