24 



TSE BONES. 



The spinal foramen, which has already assumed a somewhat considerable 

 diameter in the sixth cervical vertebra, is still larger in the geventh.i 



Fi?. 14. 



2. — Dorsal Vertehrce. 

 Gbnbbal Chabactebs.— In the dorsal vertebra; the body is very short, 

 and in front has a large slightly projecting head ; behind, it has a shallow 

 cavity. Laterally, these vertebrae present, at' the base oi the transverse 

 processes, four concave articular facets, the two anterior of which are 

 situated near the head, while the posterior two are hollowed out oi the 

 border of the articular cavity of the body. Each of these facets is joined to 



an analogous facet on the neighbouring ver- 

 tebra to form a small excavation, into which 

 is received the head of the corresponding 

 rib. The spinous process is very high, is 

 compressed on both sides, inclines backwards, 

 and its summit is terminated by a tubercle. 

 The transverse processes are unitubercular, 

 and directed obliquely outwards and up- 

 wards ; on their external aspect they have a 

 diarthrodial plane facet which corresponds 

 to the tuberosity of the rib. The articular 

 processes are narrow, and constitute simple 

 unrelieved facets cut on the base of the 

 spinous process. The posterior notches are 

 deep, and sometimes converted into foramina. 

 Specific Chabactebs. — None of the 

 eighteen dorsal vertebrse differ much from 

 the type just described ; and it is difficult 

 to establish special characters for each. 

 It is, nevertheless, possible to assign to a 

 1, Body; 2, 2, Articular fecets for the dorsal vertebra, approximately, the rank it 



head of rib ; 3, Articular facet for should OCCUpy, in accepting the following 



tuberosity of the rib ; 4, Articular facts as a guide : — 1. The vertical diameter 

 processes; 5, Spinal foramen ; 6, ^f ^j^g vertebral bodies augments progres- 

 Tuberous base of spinous process ; .i~ ,„ j_ ■, i • ^ mi'ii i 



7, Posterior articular face of body ; lively from before to behind. Their lateral 



8, 8, TransTerse processes ; 9, diameter, which determines that of the spinal 

 Superior spinous process; 10, An- canal, becomes, on the contrary, less from the 

 terior articulation of body. g^st to the tenth vertebra; after which it 



assumes increasing proportions to the last one. The articular surfaces, which 

 serve for the mutual contact of head and cavity, become larger and shallower 

 in proportion as the vertebrae are more posterior. The inferior spine on the 

 body is very salient and tuberculous in the two first vertebras, very acute in 

 the third and fourth ; it disappears in the sixth and ninth, to re-appear and 

 become more marked from the tenth to the last. 2. The intervertebral cavities, 

 intended for the reception of the heads of the ribs, diminish in depth and 

 extent from the first to the last. 3. The longest spinous process belongs to the 

 third, fourth, and fifth vertebrae ; those which follow gradually decrease to 

 the eighteenth. Their width diminishes from the second to the eighth ; it 

 afterwards increases in a progressive manner in the succeeding vertebrae; 



TYPE OF A DORSAL VERTEBRA; 

 THE FOURTH. 



' M. Goubaux has sometimes met with asymmetrical cervical vertebrae ; certain 

 vertebrae, tricuspid on one side, are only bicuspid or unieuspid on the opposite side. 



