OF VERTEBRAL COLUMN 



197 



(e) The Ligaments connecting the Transverse Processes with one another 



The intertransverse ligaments are barely Avorth the name; in the thoracic 

 region they form small rounded handles, and in the lumbar they are thin mem- 

 branous bands, quite incapable of action as bonds of union. They consist of fibres 

 passing between the ajjices of the transverse processes. In the cervical region they 

 are replaced l)y the intertransversales muscles. 



The arterial supply for the column comes from twigs of the vertel)ral. ascend- 

 ing pharyngeal, ascending cervical, superior and aortic intercostals, lumbar, ilio- 

 lumbar, and lateral sacral. 



The nerve-supply comes from the spinal nerves of each region. 



Movements. — The spinal column is so formed of a number of bones and inter- 

 vertcljral discs as to serve many purposes. It is the axis of the skeleton; u])on it 

 the skull is supported; and with it the cavities of the trunk, and the liml)s are con- 

 nected. As a fixed column it is capable of bearing great weight ; and. through the 

 elastic inten'crtebral substances, of resisting and breaking the transmission of 



Fig. "205. — The Ixterspixous and Slpra.spixuus Li(TA:\rKXTs ix the Lumbar Kegiox. 



The interspinou3 

 ll ligament 



The supraapiuoua 

 ligament 



shocks. Moreover, it is flexible, and therefore capable of movement. Now, the 

 range of movements of the column as a whole is very consideral)le; l>ut the move- 

 ments between any two vertebrae are slight, so that motions of the spine may take 

 ])lace without any change in the shape of the column, and without any marked 

 disturbance in the relative positions of the vertebrffi. It is about the pul})y part of 

 the intervertebral discs, Avhich form a central elastic pivot or ball, upon which the 

 middle of the vertebrae rest, that these movements take place. 



The amount of motion is everywhere limited by the common verteliral liga- 

 ments, but it depends partly upon the width of the bodies of the vertebra\ and 

 partly upon the depth of the discs, so that in the loins, where the bodies are large 

 and wide, and the discs very thick, free motion is permitted; in the cervical region, 

 though the discs are thinner, yet, as the bodies are smaller, almost e(jually free 

 motion is allowed. As the ball-like pulpy part of the intervertebral disc is the 

 centre of movement of each vertelira, it is olwious that the motion would be of a 

 rolling character in any direction but for the articular processes, which serve also to 

 give steadiness to the column and to assist in bearing the superincumbent weight. 



