VERTEBRAL JOINTS 89 



below, and compressed antero-posteriorly. The inlet, or superior 

 aperture, is kidney-shaped, its plane oblique, sloping down- 

 wards and forwards. The lower aperture is curved, and slopes 

 upwards along the twelfth rib to the tip of the eleventh, along 

 the cartilages of the tenth, ninth, eighth, and seventh ribs 

 to the ensiform cartilage. This aperture is closed by the 

 diaphragm. 



Joints of the Vertebral Column. 



The vertebras articulate together by their bodies and the 

 transverse processes. Each individual joint has not much power 

 of movement, but, taken altogether, the range of movement of 

 the spine as a whole is considerable. 



Intercentral Articulations. These take place between the 

 flattened surfaces of the bodies of the vertebras. Between the 

 two surfaces is a cartilaginous disc, the inter vertebral disc. In 

 the cervical and lumbar region the disc is thicker in front than 

 behind, and the reverse in the dorsal, thus helping to form the 

 curves. 



The Anterior Longitudinal ligament runs the whole length of 

 the spinal column on the anterior surface, from the first cervical 

 vertebra to the upper margin of the sacrum, and is firmly 

 attached to the intervertebral discs as it passes over them. 



The Posterior Longitudinal ligament resembles the foregoing, 

 but is placed inside the spinal canal on. the posterior surfaces of 

 thedpodies. 



Interneural Articulations. These take place between the 

 articulating processes on the pedicles of adjacent vertebras. 

 These are gliding joints, each surrounded by a thin capsule 

 lined by a synovial membrane. In addition, the ligamenta flava 

 binds together the laminas. This ligament is inside the spinal 

 canal, and resembles the anterior and posterior longitudinal 

 ligaments in being continuous throughout the length of the 

 spinal column. 



The spinous processes are attached to one another by inter- 

 spinous ligaments. In continuity with them are the supra - 

 spinous ligaments, which extend all along the spinal column 

 from tip to tip of the spines. In the cervical region these are 



