106 



MAMMALIAN ANATOMY 



from the cephalic to the caudal end, except where, at the lines of 

 laminar coalescence, it is somewhat swollen. Lateral to the line of the 

 articular processes, caudal to the lateral mass, the dorsal surface is 

 a narrow strip which slopes ventrally and laterally. 



The neural canal (Figs. 73, 74, 77) is low and wide. It is a third 

 wider and a little higher at the cephalic end than it is at the caudal 

 end. Its ventral wall, the dorsal surface of the body of the sacrum, 

 is flat from side to side and slightly convex along the median line. Its 



md Dorsal Sacral Foramen. 



FIG. 77. 



First Dorsal Sacral Foramen. Intervertebral Foramen. 



Neural Canal. 



LONGITUDINAL VERTICAL SECTION THROUGH SIXTH AND SEVENTH LUMBAR VERTEBRAE AND THE SACRUM. 



roof is flattened at the cephalic end, but is more arched at the caudal 

 end. The lateral walls terminate, at each end, at the intervertebral 

 notches, and are pierced by the intervertebral foramina leading in a 

 caudal and lateral direction into the vertical sacral canals. 



Nomenclature. The Greeks knew this region of the vertebral 

 column as the hieros spondylos, the large vertebra. The use of the 

 Latin term os sacrum, or sacred bone, has been explained by some 

 writers to be due to the fact that the bone formed an important part 

 of the sacrifices to the gods ; according to others, it was introduced 

 into anatomy through an incorrect translation of Galen's hieros, which 

 he uses, as was customary, not in the sense of holy, but in place of 

 megas, large (A.D. 131-201). The German word is das Kreuzbein, the 

 cross-bone, which, however, is said to have nothing to do with cross, as 

 it comes from the old German cruizi, an elevation, and refers to a 

 projection backward. The French use le sacrum. 



Articulation. The sacrum articulates by its cephalic end with 



