96 SKELETON. 



forwards, beneath the transverse ligament, and presses upon the 

 spinal marrow. On the contrary, when it is a simple displace- 

 ment of the oblique processes, as the odontoid process remains 

 within its boundaries, and its ligaments are only stretched, there 

 is no danger of death. Fatal accidents have happened to this 

 articulation, by holding an infant from the ground, by the two 

 hands applied to the head, from his struggles to disengage him- 

 self. A posture-maker is said to have died on the spot, from 

 communicating a rotatory motion to his trunk, while its weight 

 was sustained by inverting his head, and making the latter the 

 base of support. When the vertebras are displaced in such per- 

 sons, as well as in those hung by the neck, it is supposed that 

 this sliding of the processus dentatus from beneath the trans- 

 verse ligament takes place; as, by experiments on the dead 

 body, it is found that such displacement occurs much more rea- 

 dily than the rupture of the transverse ligament. 



2. The dorsal vertebrae are capable of but very little motion 

 in any direction. The rigidity and length of the sternum pre- 

 vent them from flexion, the overlapping and obliquity of their 

 spinous processes prevent them from extension, and the ribs pre- 

 vent them from lateral inclinations. It is, however, to be ob- 

 served, that as those obstacles are diminished, successively, in 

 the five lower dorsal vertebrae, consequently they become more 

 and more capable of motion upon each other. Luxation among 

 them, at any point, is thought to be impossible, from the strength 

 of their ligamentous attachments, and from the arrangement of 

 their articular faces. 



3. The lumbar vertebrae move with great comparative free- 

 dom upon one another; admitting, as stated, of flexion, exten- 

 sion, and lateral inclination. Below, however, they are much 

 more restrained than they are above; hence, it results, that the 

 principal seat of the motions of the trunk upon the spine, is 

 about the connexion of the lumbar and dorsal vertebrae. Dis- 

 location is here, also, thought to be impossible, from the 

 strength of their ligamentous attachments, from the great dia- 

 meters of their bodies, and from the deep interlocking of the 

 oblique processes. 



