LIGAMENTS OF THE VERTEBRAL COLUMN. 



119 



Fig. 51. 



vessels. The ligament is composed of fibres of various length closely 

 interwoven with each other ; the deeper and shorter crossing the inter- 

 vertebral substances from one vertebra to the next ; and the superficial 

 and longer fibres crossing three or four vertebrae. 



The anterior common ligament is in relation by its posterior or ver- 

 tebral surface^ with the intervertebral substances, the bodies of the 

 vertebrae, and with the vessels, principally veins, which separate its 

 central from its lateral portions. By its anterior or visceral surface it 

 is in relation in the neck, with the longus 

 colli muscles, the pharynx and the oesopha- 

 gus ; in the thoracic region, with the aorta, 

 the venae azygos, and thoracic duct; and 

 in the lumbar region, with the aorta, right 

 renal artery, right lumbar arteries, arteria 

 sacra media, vena cava inferior, left lumbar 

 veins, receptaculum chyli, the commence- 

 ment of the thoracic duct, and the tendons 

 of the lesser muscle of the diaphragm with 

 the fibres of which the ligamentous fibres 

 interlace. 



The Posterior common ligament lies upon 

 the posterior surface of the bodies of the 

 vertebrae, and extends from the axis to the 

 sacrum. It is broad opposite the inter- 

 vertebral substances, to which it is closely 

 adherent ; and narrow and thick over the 

 bodies of the vertebrae, from which it is 

 separated by the veins of the base of the 

 vertebrae. It is composed like the anterior ligament of shorter and 

 longer fibres which are disposed in a similar manner. 



The posterior common ligament is in relation by its anterior surface 

 with the intervertebral substances, the bodies of the vertebrae, and 

 with the venae basum vertebrarum ; and by its posterior surface with the 

 dura mater of the spinal cord, some loose areolar tissue and numerous 

 small veins being interposed. 



The Intervertebral substance is a lenticular disc of fibrous cartilage, 

 interposed between each of the vertebrae from the axis to the sacrum, 

 and retaining them firmly in connexion with each other. It differs 

 in thickness in different parts of the column, and varies in depth at 

 different points of its extent ; thus, it is thickest in the lumbar re- 

 gion, deepest in front in the cervical and lumbar regions, and behind 

 in the dorsal region ; and contributes, in a great measure, to the 

 formation of the natural curves of the vertebral column. 



* A posterior view of the bodies of three dorsal vertebrae, connected by their 

 intervertebral substance 1, 1. The laminae (2) have been sawn through near 

 the bodies of the vertebrae, and the arches and processes removed, in order to 

 shew (3) the posterior common ligament. A part of one of the openings in 

 the posterior surface of the vertebra, for the transmission of the vena basis 



