42 LECTURE 111. 



To each of these primary segments of the skeleton I shall, with 

 Geoffroy St. Hilaire (xiv. ii.), apply the term "vertebra": the 

 word may seem to the anthropotomist to be used in a different or 

 more extended sense than it is usually understood ; yet he is 

 himself, unconsciously perhaps, in the habit of including in certain 

 vertebrse of the human body, elements which he excludes from the 

 idea in other natural segments of the same kind ; influenced by dif- 

 ferences of proportion and coalescence, which are the most variable 

 characters of a bone. Thus the rib of a cervical vertebra is the " pro- 

 cessus transversus perforatus," or the " radix anticus processus trans- 

 versi vertebrae colli : " whilst in the chest, it is " costa," or " pars ossea 

 costfe." (xiii. 239. 250.) But the ulna is not the less an ulna in the 

 horse, because it is small and anchylosed to the radius. 



The osteology of Man, therefore, cannot be fully or rightly under- 

 stood until the type of which it is a modification is known, and the 

 first step to this knowledge is the determination of the vertebral 

 segments, or natural groups of bones, of which the myelencephalous 

 skeleton consists. 



I define a vertebra, as one of those segments of the endo-skeleton 

 xohicli constitute the axis of the body, and the protecting canals of the 

 nervous and vascidar trunks : such a segment may also support di- 

 verging appendages. Exclusive of these, it consists in its typical 

 completeness, of the following parts or elements : — 



c. A body or centrum. * , 



m 7 + zygapophysis -^i--, 



n. Two neur apophyses, y -g^ 



p. Two parapophyses. % cUapophysis.. 



jjI. Two plcur apophyses. § 



h. Two hcBmapOphyseS, || parapophysis ^_,__^ _: 



ns. A neural spine. % kl^'hsemapophysis 



hs. A hcemal spine. ** zygapophysis c3 



haemal spine 

 Ideal typical vertebra. 



* Greek, kentron, centre. Syn. Corpus vertehrcB^ , Corps de veriebre, Cuvier ; 

 Terliar-wirhel, Cams; Wirbd-korper, German^; Cycleal, Geoffroy; Cyclo-vertebral 

 element. Grant. 



■f Gr. neuron, nerve ; and apophysis, a process of bone. Syn. Arms posterior 

 vertebra, seu radices arcus posterioris. Deckplatten and Grundplatten, Carus. Doyen- 

 stiicke des Riickenwirbels, Carus. Obere Wirbelbogen, Germ. Partie annidaire, Cuv. 

 Ferial, Geof. Peri-vertebral elements, Grant. 



I Gr. para, trans, across ; and apophysis. Syn. Radix prior seu antica processus. 



neural spine 



neurapophysis 



pleurapnphysis 



' The Latin synonyms are from Soemmcrring's Classical Antliropotomy, " Dc 

 corporis humani fabrica," 1794. 



' The German synonyms are tliose of John MUllcr, Wagner, and most German 

 Zootomists, unless otherwise specified. 



