118 ARTHROLOGY, OR ANATOMY OF ARTICULATIONS 



upward in the neck, and is attached to the external occipital 

 protuberance. In the human subject it is only an intermuscular 

 septum between the two trapezii. A fibrous slip is given off 

 from its anterior surface to each cervical spinous process. 



The intertransverse ligaments are interposed between the 

 transverse processes. They are scattered fibers in the cervical 

 region, rounded cords in the dorsal, and membranous in the 

 lumbar. 



The Movements of the Spinal Column 



The movements of the spinal column are flexion, extension 

 lateral movement, circumduction, and rotation all on three 

 axes, one transverse, one anteroposterior, and one vertical. 

 Flexion is the freest of all movements; it compresses the disks 

 in front and stretches the posterior common ligament and 

 ligamenta subflava. Extension is not marked, and is limited 

 by the anterior common ligament and spinous processes. 



Flexion and extension are most free in the lumbar region 

 and least in the upper dorsal; extension is greater in the neck 

 than flexion. Lateral movement is most free in the cervical and 

 lumbar regions, limited by the approximation of transverse 

 processes. Circumduction is limited. Rotation is free in the 

 upper dorsal and absent in the lumbar region. So the cervical 

 region enjoys the greatest extent of each variety; the dorsal 

 has greatest rotation, while the lumbar has none. The head 

 and trunk may be turned through 180 degrees on either side, 

 head and neck through 79 degrees three-fifths of it is between 

 atlas and axis; back and loins through 28 degrees; and in joints 

 below this through 73 degrees. 



The movements are due largely to the shape of the disks, 

 which limit the extent of motion, but not the direction; it 

 is proportional to their height and inversely as their area. 



The vertebral articulations are supplied by the spinal nerves 

 in each region; by the vertebral and ascending cervical arteries 

 in the neck, the intercostal and lumbar below. 



* 



The Articulations of the Axis with the Atlas 



The ligaments connecting the atlas and axis are two anterior 

 atloaxoid, the posterior atloaxoid, transverse, and two capsular. 

 The two anterior atloaxoid (anterior obturator) comprise a 



