THE ARTICULATIONS OF THE VERTEBRAL COLUMN. 



153 



the bodies of one or two vertebras ; while the deepest pass only between adjacent 

 vertebrae. The fibres adhere more closely to the intervertebral discs than to the 

 bones, and none are attached over the middle of the bodies, where the ligament is 

 stretched across the transverse depression existing at this part ; and by this means 

 the anterior surface of the column, especially in the thoracic region, is rendered 

 more even. Upon the sides of the bodies there are some fibres which are thin and 

 scattered, and reach from one bone to another. 



The posterior common ligament is situated within the spinal canal, lying 

 on the posterior surface of the bodies of the vertebras ; it extends from the axis to 



Fig. 176. THE BODIES OF THREE LUMBAR VERTEBRA, SEEN FROM BEHIND, 



WITH THE POSTERIOR COMMON LIGAMENT. 3 



The arches have been removed by cutting through the pedicles. The narrow- 

 ing of the posterior common ligament opposite the middle of each body, and its 

 greater width and attachments opposite the intervertebral discs, are represented. 



the sacrum. At its upper extremity it is continuous with the 



posterior occipito-axial ligament. It is smooth and shining, and is 



broader at the upper than at the lower part of the spine. In 



the neck it extends across nearly the whole breadth of the bodies 



of the vertebras, but in the back and loins it is broader opposite 



the intervertebral discs than at the middle of the bodies, so that its margins present 



u series of points or dentations with intervening concave spaces. It adheres firmly 



to the discs and to the contiguous margins of the bodies of the vertebras, but it is 



separated from the middle of the bodies by the transverse parts of the large venous 



plexus. Between the ligament and the dura mater which lines the canal some loose 



connective tissue is interposed. 



The joints of the articular processes have each a synovial cavity sur- 

 rounded by a fibrous capsule. These capsules are shortest in the dorsal region, 



Fig. 177. THE ARCHES OF THREE DORSAL VERTEBRA, SEEN FROM 



BEFORE. ^ 



The bodies of the vertebrae have been removed by sawing though 

 the pedicles, to show the articular capsules and the ligamenta subflava 



strongest in the loins, and longest and loosest in the 

 neck. 



The ligamenta subflava are ligaments consisting of 

 yellow elastic tissue, which connect the larninas of the 

 vertebras from the axis downwards. Their fibres are 

 nearly vertical, and are attached above to the anterior 



surface of the laminas of one vertebra some distance from its inferior margin, and 

 below to the upper margin and part of the posterior surface of the laminas of the 

 succeeding vertebra. They are best seen when the arches are detached from the 

 bodies of the vertebras, and viewed from the front. Posteriorly they appear short, 

 and in the dorsal region are concealed by the prominent inferior margins of the 

 laminas and the roots of the spines. Their outer margins are close to the articular 

 processes ; their inner margins are thickened and in contact with each other beneath 

 the root of the spinous process. 



The interspinous ligaments are membranous bands in the intervals between 

 the spinous processes, each being attached to the lower border of one process and the 

 upper border of that next below it. In front they meet the ligamenta subflava, and 

 behind they join the supraspinous ligament. They are small and thin in the mid- 



