DORSAL VERTEBRAE. 



121 



CHARACTERS OF THE DORSAL VERTEBRA. 



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 

 broader in the antero-posterior than 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 adjoining vertebrae, form oval surfaces for the reception 

 of the heads of the corresponding ribs. The pedicles are directed backwards, 

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

 other region of the spine. The laminae are broad and thick, and the spinal 

 foramen small, and of a circular form. The articular processes are flat, nearly 

 vertical in direction, and project from the upper and lower part of the pedicles, 

 the superior being directed backwards and a little outwards and upwards, the 

 inferior forwards and a little inwards and downwards. The transverse processes 

 arise from the same parts of the arch as the posterior roots of the transverse 

 processes in the neck; they are thick, strong, and of great length, directed 

 obliquely backwards and outwards, presenting a clubbed extremity, which is 

 tipped on its anterior part by a small concave surface, for articulation with the 

 tubercle of a rib. Besides the articular facet for the rib, two indistinct tuber- 

 cles may be seen rising from the extremity of the transverse processes, one near 

 the upper, the other near the lower border. In man, they are comparatively 

 of small size, and serve only for the attachment of muscles. Bat, in some 

 animals, they attain considerable magnitude either for the purpose of more 

 closely connecting the segments of this portion of the spine, or for muscular 

 and ligamentous attachment. The spinous processes are long, triangular in 

 form, directed obliquely downwards, and terminating by a tubercular margin. 

 They overlap one another from the fifth to the eighth, but are less oblique in 

 direction above and below. 



Fig. 72. A Dorsal Vertebra. 



, froceat. 



Demi, facet for head of Ril 



Facet fir Tubercle of Rib 



DemifacetforJiead ofRil 



Infer. Artie. FT oo. 



The peculiar dorsal vertebrae are the first, ninth l tenth, eleventh, and twelfth 

 (Fig. 73). 



