THE THORAX 



X037 



thoracic region. It is thicker opposite the centres of the bodies 

 than elsewhere, and in these situations it fills up the concavities, 

 and so renders the front of the column less undulating than it 

 otherwise would be. Over the lateral surfaces of the bodies a few 

 scattered fibres are present, which pass from one vertebra to that 

 below. In the sacral region the anterior common ligament is 

 lost in the periosteum of the bone, but it reappears lower down as 

 the anterior sacro-coccygeal ligament. The anterior common 

 ligament is serially continuous superiorly with the anterior atlanto- 

 axial ligament. 



The posterior common ligament is situated within the spinal 

 canal, and extends over the posterior surfaces of the bodies of the 



Fig. 427. — Posterior Common Liga- 

 ment OF THE Bodies of the 

 Vertebrae. 



Fig. 428. — Intervertebral Discs 

 (Anterior View). 



vertebrae and intervertebral discs. It is broader above than below, 

 and consists of glistening fibres, which extend from the axis to the 

 first coccygeal vertebra, its sacral part, however, being very narrow 

 and delicate. Its fibres are firmly attached to the intervertebral 

 discs and margins of the vertebral bodies, but they are separated 

 from the centres of the bodies by the transverse venous com- 

 munications between the anterior intraspinal veins. In the cervical 

 region the ligament is of almost uniform breadth, being expanded 

 over the vertebral bodies, as well as over the intervertebral discs. 

 In the thoracic and lumbar regions, however, it is narrow opposite 

 the vertebral bodies, and broad opposite the inter\'ertebral discs. 

 Its margins, therefore, present dentations, which give it a denticu- 

 lated appearance. The arrangement of its fibres is similar to the 



