DORSAL VEllTEBK.^^. 



13 



the greater number of instances, there are two costal snrfaces on each 

 side, — one on the superior, the other on the inferior border, — so placed 

 that each completes, with that of the adjacent vertebra, a cavity for the 



Fig. 8. — Sixth Dorsal Vertebra. (A. T.) i 



A, viewed from above ; B, viewed from tlie 

 right side. 1, the body ; 2, the pedicle ; 3, the 

 lamina ; 4, vertebral ring, nearlj' circular ; 5, 

 spinous process ; 6, transverse process ; 7, 7', 

 superior and inferior articulating processes ; c, c', 

 superior and inferior facets on the body for the 

 articulation of the head of the rib ; d, facet, on 

 the transvei'se process for the articulation of the 

 tubercle of the rib. 



head of one rib. The body of the first 

 dorsal vertebra is, however, distinguished 

 by having on each side, near its upper 

 border, a complete articular surface for 

 the head of the first rib, liesidcs a smaller 

 surface on the lower border for one 

 facet of the second rib. On the bodies 

 of the tenth, eleventh, and twelfth ver- 

 tebra3, there is only one costal surface 

 for the corresponding ribs ; that on 

 the tenth vertebra is usually complete, 

 when there is necessarily no costal sur- 

 face at the lower border of the ninth vertebra, iDut only one such 

 surface, a demi-facet at its U]")per border for the ninth rib. 



The lamitUB broad aud flat are imbricated or sloped one pair over 

 another like tiles on a roof. The superior notches are very shallow, the 

 inferior comparatively deep. 



The spinous ^^roccss, described as bayonet-shaped, is three-sided, and 

 terminates in a slight tubercle. It is longest and has the greatest 

 downward inclination in those toward the middle of the series. 



The transverse procfsses are directed outwards and backwards, and 

 terminate in a rough tubercle which presents anteriorly a smooth 

 surface for articulation with the tubercle of a rib. This articular 

 surface is wanting on the eleventh and twelfth vertebras. In several of 

 the lowest vertebras the extremity of the transverse process when looked 

 at from behind presents three slight elevations, named the external, 

 internal, and inferior tubercles. These are best marked on the twelfth 

 vertebra, and correspond respectively to the transverse, mammillary, 

 and accessory tubercles to hQ afterwards noticed on the lumbar vertebrae. 

 (See Figs. 9 and 10, e,f, (>.) 



The articular processes have their cartilaginous surfaces nearly 

 vertical. Those of the superior processes look backwards, slightly 

 upwards and outwards, those of the inferior look forwards, slightly 

 downwards and inwards. But the superior articular processes of the 

 first dorsal vertebra are similar to those of the cervical, and the inferior 

 of the twelfth dorsal to those of the lumbar vertebrae. 



T^he foramen is nearly circular, and is smaller than in the cervical or 

 the lumbar region. 



Lumbar Vertebrae. — These are five in number, larger than the 



