n.] THE SPIXAL SKELETON. 27 



The first of these two masses, termed the sacrum, comes 

 immediately beneath the lumbar vertebrae, and affords attach- 

 ment on each side to one of the haunch, or hip, bones. Five 

 or six sacral vertebrae coalesce to form the sacrum. 



The second and much smaller bony mass, termed the 

 coccyx, 1 is made up of three or four small and imperfect 

 vertebrae, named coccygeal. 



8. Before proceeding to consider more carefully the different 

 vertebrae, a DORSAL VERTEBRA may first be described as a 

 type. 



* 



FIG. 39. A DORSAL VERTEBRA. 



c, centrum ; s, neural spine ; d, tubercular or transverse process ; /, capitular 

 process, or articular surface for the head of a rib ; /', small articular surface 

 for part of the head of the succeeding rib ; z, upper articular process, or 

 prezygapophysis ; z ', lower articular process, or postzygapophysis. 



From each outer angle of the posterior surface of its 

 centrum there springs a pier of the neural arch. Each of 

 these two piers is termed a. pedicle. 



From the hinder end of each pedicle a flat plate of bone 

 projects backwards and towards the middle line, till the two 

 plates meet and thus complete the neural arch. Each such 

 plate is termed a " lamina '' or neural lamina. 



At the point of junction of the laminae a single median 

 process runs backwards and downwards. This is the spinous 

 process, or neural spine? 



From the junction of each lamina with its pedicle another 

 process, ending -bluntly, juts outwards and backwards. This 

 is called the transverse process, and there are two to every 

 .iorsal vertebra. 



From the upper and outer part of each lamina a brnall 

 process projects upwards, with a smooth surface on it which 



1 From its fancied resemblance to a cuckoo's beak KOKKV!-, a cuckoo. 



2 Sometimes neurapophysis, from teDpuir, a nerve, and u7r6<pi;<7(<;, a process. 



