4 Vetcnnary Obstetrics 



coxae. The inferior surface contributes to the formation of the 

 pelvic roof, is concave from before to behind, essentially plane 

 from side to side and shows transverse lines of demarcation be- 

 tween the individual vertebrae in the form of ridges varying in 

 prominence with species, age, breed and individual. It is alleged 

 that the sacrum varies according to sex, the articular elevations 

 being, it is claimed, less prominent in the female. We have not 

 been able to verify this claim by the study of specimens. 



Fig. I. Sagittal Section of the Pelvis ok the Mare, 



SHOWING H'MHO-SaCRAL NERVES. 



S, First sacral vertebra. L, Last lumbar vertebra. A, Last lumbar 

 nerve, passing passing over lumbo-sacral eminence. E, Gluteal nerves. 

 O, Obturator nerve entering foramen. 



The spinal canal extends through the .sacrum and is occu- 

 pied by the terminal nerves of the spinal cord. The inferior sur- 

 face of the bone shows a series of paired openings, through which 

 the sacral nerves emerge to take a prominent part in the forma- 

 tion of the lumbo-.sacral plexus. Most of these emerge in sucli a 



