548 SURGICAL APPLIED ANATOMY. [Chap. xxiv. 



parts. In the dorsal spine the laminae and articular 

 processes are always torn when displacement occurs. 

 In the lumbar region the articular processes usually 

 escape fracture, although they are violently torn 

 asunder. In all cases there is more or less laceration 

 of the intervertebral discs, the supraspinous, inter- 

 spiiious, and capsular ligaments are torn, as are also 

 the ligamenta subflava. When the bodies are much 

 crushed and displaced the anterior and posterior 

 common ligaments are commonly ruptured. 



2. In the fracture - dislocations due to direct 

 violence the lesion may be at any part of the spine. 

 Some form of direct violence is applied to the back, 

 and the column tends to become bent backwards at 

 the spot struck. In the previous class of injuries it 

 will be noted that the anterior segments of the ver- 

 tebrae suffer compression, while the posterior suffer 

 from the effects of laceration and a tearing asunder of 

 their parts. In lesions due to direct violence the 

 circumstances of the injury are reversed, the posterior 

 segments tend to be crushed together, while the bodies 

 on the front of the spine are separated. 



Much displacement is very rarely met with in thifc 

 form of accident. To produce separation of the ver- 

 tebrae the violence must be very extreme, and as a 

 rule the force expends itself upon a crushing of the 

 hinder portions of the spinal segments. It follows 

 from this, also, that injury to the cord is less common 

 and less severe in lesions due to direct violence than 

 in those due to indirect violence. In the atlo-axial 

 region the atlas and occipital bone have been dislocated 

 from one another by direct violence, although the 

 most frequent lesion is a dislocation of the former 

 forwards upon the axis, a lesion usually, if not always, 

 associated with fracture of the odontoid process. 



The spinous processes may be broken off as a ro- 

 sult of well-localised blows. The prominent spines in 



