DORSAL VERTEBRA. 149 



the existence of a very long and prominent spinous process ; hence ine name 

 "vertebra prominens." This process is thick, nearly horizontal in direction, not 

 bifurcated, and has attached to it the ligamentum nuchae. The transverse process 

 is usually of large size, especially its posterior root ; its upper surface has usually 

 a shallow groove, and it seldom presents more than a trace of bifurcation at its 

 extremity. The vertebral foramen is sometimes as large as in the other cervical 

 ertebrie. but is usually smaller on one or both sides, and sometimes wanting. On 

 the left side it occasionally gives passage to the vertebral artery ; more frequently 

 the vertebral vein traverses it on both sides ; but the usual arrangement is for both 

 artery and vein to pass in front of the transverse process, and not through the 

 foramen 



Characters of the Dorsal Vertebrae. 



The Dorsal Vertebrae are intermediate in size between those in the cervical and 

 those in the lumbar region, and increase in size from above downward, the upper 



Superior articular process.- _ 



- Demi-facet for head of rib. 



Facet for tubercle of rib 



Demi-facet for head of rib. 

 Inferior articular process. 



FIG. 113. A dorsal vertebra. 



vertebrae in this segment of the spine being much smaller than those in the lower 

 part of the region. The dorsal vertebrae may be at once recognized by the pres- 

 ence on the sides of the body of one or more facets or half-facets for the heads of 

 the ribs. 



The bodies of the dorsal vertebrae resemble those in the cervical and lumbar 

 regions at the respective ends of this portion of the spine ; but in the middle of 

 the dorsal region their form is very characteristic, being heart-shaped, and as 

 broad in the antero-posterior as in the lateral direction. They are thicker behind 

 than in front, flat above and below, convex and prominent in front, deeply concave 

 behind, slightly constricted in front and at the sides, and marked on each side, 

 near the root of the pedicle, by two demi-facets. one above, the other below. These 

 are covered with cartilage in the recent state, and, when articulated with the adjoin- 

 ing vertebrae, form, with the intervening fibro-cartilage, oval surfaces for the 

 reception of the heads of the corresponding ribs. The pedicles are directed back- 

 ward, and the inferior intervertebral notches are of large size, and deeper than in 

 any other region of the spine. The la mince are broad, thick, and imbricated 

 that is to say. overlapping one another like tiles on a roof. The spinal foramen is 

 small, and of a circular form. The spinous processes are long, triangular in form 

 (bayonet-shaped), directed obliquely downward, and terminate in a tubercular 

 extremity. They overlap one another from the fifth to the eighth, but are less. 



