18 



THE BONES AND JOINTS. 



Fig- 5- 



in the dorsal vertebrae of man ; they are directed backwards and 

 provided with cartilaginous epiphyses. The spinous processes of the 

 sixth and seventh are shorter, compressed from side to side, project 



directly upwards, and are usually 

 without cartilaginous epiphyses ; 

 that of the eighth is still shorter. As 

 regards the spinous processes, those of 

 the third, fourth, and fifth vertebrae 

 resemble those of the dorsal vertebrae 

 in man; those of the sixth, seventh, 

 and eighth, lumbar vertebrae. The 

 ninth has either no spinous process or 

 only a rudimentary one. The first and 

 second vertebrae may be looked upon 

 as cervical vertebrae : the second has 

 a short spinous process with a car- 

 tilaginous epiphysis. In the first, the 

 cartilage which unites the two halves 

 of the arch represents the rudiment 

 of a spinous process. 



II. DESCRIPTION OF PARTICULAR 

 VERTEBRAE. 



1. The atlas or first vertebra has 

 a thin body, compressed from above 

 downwards, and an arch. The body 

 has posteriorly a slightly raised, car- 

 tilaginous, articular head, which is 

 broader transversely : in front it has 

 two oval articular facets, which are 

 separated from each other by a median 

 projection. Each facet is concave, 

 and directed forwards, outwards, and 

 slightly upwards. The arch is com- 

 pleted above by cartilage, which pro- 

 jects slightly to form the rudiment of a 

 spinous process. The hinder margin of 

 the arch bears two articular processes. 

 Transverse processes are wanting. 

 2, The second vertebra presents all the general characters of an 



Vertebral column of Hana esculenta, from 



above, twice nat. size, 

 i to 9 First to ninth vertebrae, 

 c Urostyle. 



o o Articular processes. 

 sc Facets for articulation with the nroatyle. 

 1 1.' Transverse processes. 



