THE ATYPICAL DORSAL VERTEBRA 25 



lower border; these, when the vertebrae are articulated, form 

 with the facet on the intervertebral fibrocartilage a complete 

 facet for the head of a rib. 



Between the neck of a rib and the transverse process articu- 

 lating with it is the costo trans verse foramen. In the cervical 

 region this is represented by the vertebral foramen, and in 

 the lumbar region the space is filled by the bony mass of the 

 transverse process. 



The laminae are broad and flat, and overlap each other. 

 The spinal foramen is circular and smaller than in other regions. 

 The pedicles are directed backward from the upper part of the 

 body. The inferior intervertebral notches are deeper than in 

 any other region of the spine. 



The superior vertebral notches are shallow or absent. 



The spinous processes are bayonet-shaped, and terminate 

 in a slight tubercle. They are longest and most oblique, sloping 

 downward and back progressively, from the fifth to the eighth. 



The transverse processes are situated behind the articular 

 processes and pedicles, and are directed outward and backward, 

 and terminate in a clubbed extremity, which presents anteriorly 

 a small concave articular surface, for the tuberosity of a rib, 

 and also three indistinct tubercles, one from the upper border, 

 one from the lower, and the third externally, for muscular 

 attachments. The articular processes are nearly vertical, with 

 smooth flat surfaces. The superior look back, a little outward 

 and up. The inferior look in the reverse direction. 



The Atypical Dorsal Vertebrae 



The first, ninth, tenth, eleventh, and twelfth are to be 

 distinguished. The first dorsal resembles the seventh cervical. 

 Its body above is transversely concave and lipped. The 

 superior vertebral notches are deep, the superior articular 

 processes are oblique, and the spinous process is nearly hori- 

 zontal. On the side of the body, close to the upper border, 

 are a whole facet for the first rib and a very small demifacet 

 below for the second rib. 



The twelve ribs correspond to twelve joint surfaces, but 

 these are divided, so that only the first, tenth, eleventh, and 

 twelfth present single facets; the first in addition has a half- 

 facet, and the ninth has one demifacet above and none below. 



