308 



THE AKTICULATIONS OK JOINTS. 



Root of 

 vertebral arcli 

 divided 



The laminae of adjoining vertebrae are bound together by the ligamenta flava 

 (O.T. subflava) (Fig. 295), which consist of yellow elastic fibres. The ligamenta 

 flava close the vertebral canal in the intervals between the laminae. Each ligament 

 is attached superiorly to the anterior aspect of one lamina at a short distance above 

 its inferior border, and inferiorly it is attached to the posterior aspect of the 

 subjacent lamina. 



In the thoracic region, where the imbrication of adjoining laminae is a prominent 

 feature, these ligaments are not so distinctly visible from behind as they are in the 

 regions where imbrication of the laminae is not so marked. 



Laterally they extend as far as the articular capsules, while medially the margins 

 of the ligaments of opposite sides meet under cover of the root of the spinous 

 process. 



Contiguous spinous processes are also attached to each other by ligamenta 

 interspinalia (interspinous ligaments) (Fig. 292). These are strongest in the lumbar, 

 and weakest in the thoracic region. Each consists of layers of obliquely inter- 

 lacing fibres which spring from near the tips of the two adjacent spinous process 



and radiate to their op- 

 posing margins. In the 

 antero - posterior direc- 

 tion they extend from 

 the base to the tip of 

 the spinous process. 



The ligamenta supra- 

 spinalia (supra-spinous 

 ligaments) (Fig. 292) 

 consist of longitudinal j 

 bands of fibres of varying I 

 lengths. They extend] 

 from spine to spine,] 

 being attached to their! 

 tips, and are situated 

 superficial to, although] 

 in continuity with, the! 

 ligamenta interspinalia. 



In the cervical region] 

 this series of ligaments; 

 is extensively developed. i j 

 where they project back- 1 

 wards from the spinoug] 

 processes between the 3 

 muscles of the two sides! 

 of the neck in the form oil 

 an elastic partition called 5 

 the ligamentum nuchae. 



The antero-posterior extent of the ligamentum nuchae increases as it approaches 

 the occiput, where it is attached to the external occipital crest from the externa]j 

 occipital protuberance to the posterior border of the foramen magnum. Its posteriori 

 margin is free, and extends from the external occipital protuberance to the spine j 

 of the vertebra prominens. 



Between the transverse processes there are ligamenta intertransversaria, which- 

 consist of vertical fibres extending from the postero-inferior aspect of one transverse! 1 

 process to the superior margin of that next below. These ligaments are generally I 

 absent from the cervical and upper thoracic regions. 



Sacro-coccygeal Symphysis. The last piece of the sacrum is joined to the! 

 first piece of the coccyx by an intervertebral fibro-cartilage, and the jimctiorjlJ 

 is rendered more secure by the presence of certain strong ligaments. A lig. sacro 

 coccygeum anterius, continuous with the lig. longitudinale anterius, is placed irj! 

 front. A lig. sacrococcygeum posterius, which stretches downwards from the sharjll 

 border of the lower opening of the sacral canal, strengthens the joint behind. ^J ! 



FIG. 295. LIGAMENTA FLAVA AS SEEN FROM THE FRONT AFTER RE- 

 MOVAL OF THE BODIES OF THE VERTEBR-E BY SAWING THROUGH THE 



ROOTS OF THE VERTEBRAL ARCHES. 



