22 VERTEBRAL COLUMN. 



On examination of the series of transverse processes, a certain amount of correspon- 

 dence cannot fail to be noticed between the anterior divisions of those of the cervical 

 vertebras and ribs; especially when it is considered that in certain instances those of 

 the seventh cervical vertebra are replaced by ribs which are articulated in two places 

 with the vertebra; and that in the neck of saurian reptiles short ribs are found very 

 similar in appearance to the anterior divisions of the transverse processes in the 

 human subject. On the other hand, these processes differ from ribs in being for the 

 most part ossified in continuity with the arch ; and on that account some anatomists 

 prefer to compare them with the costal facets on the dorsal vertebrae, and with pro- 

 cesses on which in birds and reptiles those facets are elevated. The transverse, mam- 

 millary, and accessory processes of the lumbar vertebrae lie in series, as has been 

 seen, with the three sets of tubercles on the transverse processes of the twelfth and 

 other dorsal vertebrae, whence it may be argued, as has been done by Retzius, that 

 the whole transverse process of a dorsal vertebra corresponds to the three processes 

 of a lumbar vertebra. At the same time, the mammillary processes are not mere 

 subsidiary parts developed on the transverse processes, for in some animals, as the 

 hedgehog and the armadillo, they are of much greater size than the transverse pro- 

 cesses themselves, continue distinct from them in nearly the whole length of the 

 thoracic region, and may be seen to lie in series with prominences on the articulating 

 processes of the cervical vertebrae. The lumbar transverse processes are not without 

 a certain degree of correspondence with ribs, which is illustrated by the first of the 

 series being sometimes replaced by a short thirteenth rib on one or both sides, and is 

 also indicated by the existence on the upper borders of the lumbar transverse processes 

 of grooves, sometimes pretty distinct, which lie in series with the intervals between 



Fig. 20. Fig. 20. OSSEOUS PART OF THE FIRST- VERTEBRA OF THE 



SACRUM OF A PERSON OF FOUR OR FIVE YEARS OLD. J 



1, the body ; 2, 2, the large lateral masses between 

 which and the body and the transverse processes deep 

 fissures are seen running backwards. 



the necks of the ribs and the dorsal transverse processes. 

 In the sacrum, the special lateral centres of ossification 

 in the three upper vertebrae may, very probably, be 



regarded as costal elements. (Retzius, "Muller's Archiv," 1849 ; J. Miiller, " Vergl. 

 Anat. der Myxinoiden;" August Miiller, "Muller's Archiv," 1853; Humphry, 

 "Treatise on the Human Skeleton ; " Cleland, in " Nat. Hist. Review," 1861 and 1863.) 

 It is not to be wondered at that the vertebral column, from its being the most 

 regularly segmented structure in the body, as well as from its forming the basis of the 

 osseous system, should have held a prominent place in the various schemes, according 

 to which it has been attempted to resolve the skeleton into a certain number of 

 elements, repeated in modified forms in the different segments. Among the various 

 schemes of this description may be mentioned those of Oken, Carus, Geoffroy St. 

 Hilaire, Owen, Maclise, and Goodsir. (Oken, "Physiophilosophie,"and in "Isis," 1817, 

 1819, 1820 ; C. G. Carus, " Lehrbuch der Zootomie," 2nd edit. ; Geoffroy St. Hilaire, 

 "Philosophic Anatomique;" Owen, "On the Archetype and Homologies of the 

 Vertebrate Skeleton ; " Maclise, " Comparative Osteology," and the Article " Skele- 

 ton " in " Todd's Cyclopaed. of Anat. and Physiol. ; " Goodsir, " Edinburgh New 

 Philosophical Journal," 1857, p. 118.) 



Based upon morphological views, there has likewise been introduced by Owen 

 a system of nomenclature, which being adhered to in his descriptive writings, 

 and adopted more or less by various English writers, demands attention. In that 

 system the word vertebra is employed to signify a segment of the skeleton, the term 

 centrum is preserved in its usual signification, the laminae are called neurapophyses, 

 the spine the neural spine, the articulating processes zygapopliyses, the ribs pleura- 

 pophyses, the mammillary processes metapophyses, and the accessory processes 

 anapophyses. Two descriptions of transverse processes are distinguished, viz., the 

 diapophyses and the parapoplyses ; the dorsal transverse processes and the posterior 

 parts of the cervical transverse processes being examples of the first, while the anterior 

 parts of the cervical transverse processes are referred to ^the second. The ideal 



