I038 



A MANUAL OF ANATOMY 



Fig. 429. — Intervertebral Disc 

 (Transverse Section). 



arrangement of those of the anterior common ligament. The 

 posterior common ligament is serially continuous superiorly with 

 the posterior occipito-axial ligament. 



The intervertebral discs are situated between the adjacent sur- 

 faces of the bodies of the vertebrae, and they constitute the chief 

 bondof union between them. 



Their outline corresponds to ^'""■^' "'^ Fibro-lambar Portion 



that of the bodies between 

 which they are placed, and 

 they are elastic and com- 

 pressible. Except in early 

 life, the first or highest disc 

 is situated between the 

 bodies of the axis and the 

 third cervical vertebra, and 

 in the adult the last or 

 lowest disc is situated be- 

 tween the bodies of the fifth 

 lumbar and first sacral ver- 

 tebrae. 



Each disc is composed 

 of a circumferential fibrous 

 part, disposed in the form 

 of superimposed laminae, 

 and a central portion, which 

 is soft and pulpy. The external laminar part forms more than half of 

 the disc, and is composed of fibrous tissue and fibro-cartilage. As 

 seen in transverse section the laminae are arranged concentrically 



around the central pulp, 



Fibro-laminar Portion ^j^-^j^ ^^^^ ^j^^^jy CmbraCC 



i ?'"'P and compress. The fibres 



/>VL'i.v..'!^;r:c#'^Mi;;i;;.. A of which they are composed 



are arranged in parallel 

 bundles, which extend 

 obliquely between the adja- 

 cent surfaces of the verte- 

 bral bodies, being attached 

 to the layer of hyaline car- 

 tilage which covers them. 

 The fibres of successive 

 laminae pass obliquely in 

 opposite directions, and 

 are disposed thus X. The 

 outer laminae consist of 

 fibrous tissue, but the 

 majority are composed of 

 white fibro-cartilage. As seen in vertical section the outermost 

 laminae are bent outwards, and those around the central pulp 

 are bent inwards towards it, this arrangement contributing to 



Capsule of 

 rtic. Processes 



Fig, 430. — Vertical Sagittal Section of 

 Two Intervertebral Discs. 



