chap, xxiv.i THE SPINE. 549 



the lower cervical region and the long processes of the 

 dorsal tract of the column are those that usually suffer. 

 The lumbar spines are less frequently broken, being 

 comparatively small and well protected by the great 

 muscles of the back. 



The transverse processes and laminae can scarcely 

 1)6 fractured alone. 



In several instances of fracture-dislocation and of 

 fracture alone the spine has been trephined, or rather 

 portions of the laminae and spinous processes have 

 been resected (Laminectomy). By this means the 

 spinal canal has been freely opened up, effused blood 

 has been allowed to escape, and the cord has been 

 freed from pressure. The laminae are divided as near 

 the transverse process as possible, and the tough 

 ligamenta subflava require careful division. Dr. 

 White, of Philadelphia, has collected (1889) thirteen 

 recent examples of operation for fracture with only 

 one death. 



The column is reached through a median incision, 

 and the great muscular masses are cleared from the 

 spinous processes and laminae on either side. The 

 wound being nearly median, the bleeding is not 

 excessive. 



This operation has also been carried out with 

 success in cases of paralysis due to the pressure upon 

 the cord by displaced bone or inflammatory exudations, 

 in caries of the spine (Pott's disease). It has to be 

 noted, however, in the last-named class of case, that 

 the condition exhibits a tendency to spontaneous cure. 



The spinal cord is in the adult about eighteen 

 inches in length, and extends from the lower margin 

 of the foramen magnum to the lower edge of the body 

 of the first lumbar vertebra. In some cases it ends at 

 the second lumbar, and in other instances at the last 

 dorsal vertebra. It is to be noted also that in flexion 

 of the spine the cord is a little raised. In the earlier 



