OSSEOUS SYSTEM OF MAMMALIA, 



63 



the sacrum, or sacral portion of the column. The vertebrae, included in 

 this division, are termed lumbar ; and they may be at once distinguished, 

 especially in the human subject, by their superior size, and the great 

 development of the transverse processes (see human skeletons, figs. 12, 

 13, 14), indicating the volume of the lumbar muscles. In the Horse, the 

 Ox, the Antelope, and especially in the Porpoise, Whale, and other 

 Cetacea, the development of the transverse processes is both conspicuous 

 and characteristic. 



With respect to the spinous processes of the lumbar vertebrae, they 

 are less elongated than those of the dorsal, and especially of the anterior 

 dorsal vertebrae ; and, in general, their direction is opposite. The spi- 

 nous processes of the dorsal vertebrae point obliquely backward, those 

 of the lumbar vertebrae obliquely forward ; at least, as a general rule : 

 whence it would seem to follow, that, at the point of junction between 

 the dorsal and the lumbar portions of the vertebral column, the spinous 

 processes of each part must meet in abrupt opposition. This is not 

 precisely the case ; for, if it were, the centre of motion in the spinal 

 column would necessarily lie between two vertebrae, and the flexure 

 would be acute. There is, however, a transition from the posterior- 

 oblique bearing of the spinous processes of the dorsal to the anterior- 



rigs. 59 to 63. Lumbar vertebrae, in different aspects. 



Fig. 59, Anterior. 60, Posterior. 61, Superior. 62, Inferior. 63, Lateral. a, body; ft, spinous process; c, c, oblique 

 processes ; rf, d, transverse processes ; e, spinal canal. (The same letters refer to the same part in all the above tigures.) 



oblique bearing of those of the lumbar vertebrae ; the processes of the 

 lower dorsal and those of the superior (or anterior) lumbar vertebrae 



