CHAP. IV.] 



FIBRO-CARTJLAGE. 



95 



Fig. 17. 



surfaces, placed in the cavity of diarthrodial joints between the 

 articular surfaces of the bones. These are the menisci of authors ; 

 they exist in the temporo-maxillary, the sterno-clavicular, and the 

 knee joints, and between the scaphoid and lunar, and lunar and cunei- 

 form bones, c. As triangular edges to the glenoidandcotyloid cavities 

 of the shoulder and hip joints. These are styled circumferential. 



In examining these different forms of fibro-cartilage, some varie- 

 ties are met with deserving of a brief notice. 



The inter vertebral discs consists of concentric layers of white 

 fibrous tissue, placed vertically between the surfaces of the vertebrae: 

 although the layers are vertical, 

 the fibres of which each layer is 

 composed, are directed obliquely 

 from above downwards, and the 

 direction of the fibres of one layer 

 is such as to decussate with those 

 of the layer immediately behind 

 it. Each pair of layers of fibrous 

 tissue is separated by a lamina 

 of cartilage. This arrangement 

 belongs to rather more than 

 the outer third of the disc: the 

 central portion is occupied by 

 a soft, yielding, pulpy matter, 

 which, when a disc is cut horizon- 

 tally, rises up considerably above 

 the surrounding level. This soft 

 mass consists of a few bundles of 



wliifr filvrrma ticnp (wttiTir -fihrvasA Elementary structures from an intervertebral 

 >SUe (^Wavy nOieSj, ^^^^ cartilage-cells lying amongst the 



with numerous nucleated 

 very variable in shape and size, 

 loosely interspersed. It is girt by 

 the surrounding vertical fibrous 

 layers arid their interposed cartilaginous lamellae, and also com- 

 pressed by the vertebrae between which it is placed j the pulpy 

 matter being separated from immediate contact with the surfaces 

 of the vertebrae by the interposition of thin layers of cartilage. 



In the menisci the white fibrous tissue predominates considerably 

 at their circumferences, while the cartilage chiefly abounds in the 

 centre. Those of the knee joint and temporo-maxillary joint are 

 the densest ; that of the sterno-clavicular is softer and more carti- 

 laginous. 



Oplls wn ite fibrous tissue. The remaining objects are 

 a .> from the central pulpy substance, and exhibit 

 various forms of cell. In several of these there is 

 an appearance of multiplication by subdivision of 

 the nucleus, and some seem attached by a fibrous 

 tissue. The full meaning of this does not yet 

 appear. 



