254 THE ARTICULATIONS OR JOINTS. 
anterior convexity which characterises the spinal column in these two regions. In 
the dorsal region the discs are thinnest on their anterior aspects in correspondence 
with the anterior concavity of this section of the spine. 
Each disc consists of a circumferential portion (annulus fibrosus), formed for 
Intervertebral foramen 
Vertebral body 
_Ligamentum flavum 
; or subflavum 
Intervertebral disc : 
Ligamentum 
interspinale 
Ligamentum 
supraspinale 
Nucleus pulposus - 
a teed rer Pt ioe 
Spinous process 
Fria. 198.—MEsIAL SECTION THROUGH A PORTION OF THE LUMBAR PART OF THE SPINE. 
the most part of oblique parallel fibres running from one vertebra to the other. 
Horizontal fibres are also found. The axial or central part of the disc is elastic, 
soft, and pulpy (nucleus pulposus).! 
The upper and lower surfaces of the disc are closely adherent to the adjoining 
oD ear Si). ee i ele 
Wyre ‘\ Anterior common ligament 
Anterior or 
superior costo- 
transverse 
ligament 
Three slips of al 
stellate ligament | Go 
a 
Anterior or 
superior costo- 
transverse 
ligament 
Fa 
ANTERIOR CoMMON LIGAMENT OF THE VERTEBRAL COLUMN, AND THE COSTO-VERTEBRAL 
JOINTS AS SEEN FROM THE FRONT. 
Fia. 199. 
epiphyseal plates of the vertebral bodies, and as ossification advances, the distine- 
tion between epiphyseal plates and vertebral body disappears. 
As a rule the transverse diameter of the disc corresponds to that of the verte- 
bral bodies which it joins together; but in the cervical region, where the lower 
' This pulpy substance does not present a joint cavity, but in certain cases it is more dt less divided 
by fissures which occupy a transverse horizontal direction. 
