VEETEBRAL COLUMN 113 



the thoracic region the laminae and the upper surfaces of the trans- 

 verse processes are involved to form a shallow groove which lodges 

 the spinal muscles. From the eleventh thoracic to the end of the 

 lumbar region the strip is made up of lamina? only, and the high 

 cephalic articular processes convert it into a narrower longitudinal 

 groove, deeper at the cephalic end of each vertebra and shallower as 

 the lamina rises at its caudal end. The lateral strip becomes wider in 

 the sacrum, and in the tail is continued on the dorsal surface of the 

 transverse processes. 



The articular processes of the vertebra? in the cervical region lie 

 far away from the median line ; they are nearer the median line and 

 indistinct in the thoracic region back to the eleventh vertebra, where 

 they become prominent, develop mammillary processes, and again 

 gradually get further away from the median line. In the sacral 

 region they are coalesced, but become distinct again in the first few 

 caudal vertebrae. 



The dorsal aspect shows, finally, the cephalo-caudal diameter and 

 the lateral extent of all the transverse processes. The cephalo-caudal 

 diameter is greater in the atlas, much smaller in the pointed processes 

 of the axis, small in the remaining cervicals, and greater at the be- 

 ginning of the thoracic region. It then gradually increases to the 

 tenth, inclusive, after which the transverse processes are transformed 

 into the mammillary and accessory processes. What are known as 

 the transverse processes on the lumbar region begin at a lower level 

 as narrow plates, which increase in cephalo-caudal diameter and 

 become pointed and curved toward the head as we proceed toward the 

 sacral region, where the transverse processes are united. The trans- 

 verse processes in the vertebra? of the tail are narrow and curved in 

 a caudal direction. The length of the transverse processes, measured 

 on a transverse line from their points of origin on the vertebra to 

 their tips, is liable to variation in the different regions of the vertebral 

 column. The length is great in the atlas, small in the axis, whence 

 it gradually increases to the seventh cervical, beyond which it de- 

 creases gradually to the tenth thoracic inclusive. From the first 

 to the sixth lumbar it increases again, remains the same at the 

 seventh, and then decreases, with sometimes a slight increase at the 

 first few caudals, until the process disappears in the terminal caudal 



region. 



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