“7? 
ance in the ale of the 26th vertebra. He thus assumes that the ale of the 25th vertebra may 
be regarded as the main and primary attachment with the ium. His conclusions, based on a 
large number of observations, are at variance with Rosenburg’s views, for, according to his opinion, 
liberation of the first sacral segment is more common than assimilation with the fifth lumbar ° 
vertebra, and assimilation of the first coceygeal vertebra with the sacrum is more common than 
liberation of the fifth sacral, thus leading to the inference that the sacrum tends to shift back- 
wards more often than forwards. 
Ossification of the Vertebrz.—The vertebree are developed by ossification of 
the cartilage which surrounds the notochord and which passes backwards over the sides of 
the neural canal. The centres for the bodies first appear in the 
are! lower thoracic vertebrae about the tenth week. An oval nucleus 
for develops in each body. At first it is placed dorsal to the noto- 
Puewal chord, but subsequently surrounds and causes the disappearance 
of that structure. Occasionally, however, the primitive centre 
appears to be formed by the coalescence of two primary nuclei. 
Support is given to this view by the occasional occurrence of 
88 OSTEOLOGY. 
Centre for F ‘ i P 
body vertebree in which the body is developed in two lateral halves, 
Fic. 67,.—Ossrication OF im cases where only one-half of the body persists (Turner) ; 
OF VERTEBRE. normally, however, it is impossible to make out this division. From 
these single nuclei the bodies are developed, the process extending 
up and down the column until, by the fifth month, all the centra possess ossific deposits, 
> 
Fic. 68.—OssIFICATION OF VERTEBRE. 
Cervical vertebra, 20. Synchondroses close about 3rd year. 
1. Centre for body. 21. Centre for summit of odontoid process ; appears 
2. Superior epiphysial plate. 3rd to 5th year, fuses 8th to 12th year. 
3, Anterior bar of transverse process developed by 22. Appears about 5th or 6th month; unites with 
lateral extension from pedicle. opposite side 7th to 8th month. 
4, Neuro-central synchondrosis. 23, Synchondrosis closes from 4th to 6th year. 
Feaimferior epiphysial plate. 24, Inferior epiphysial plate ; appears about puberty, . 
unites about 25th year. 
Lumbar vertebra. 25. Single or double centre for body ; appears about 
6. Body. 5th month. 
7- Superior epiphysial plate. 
8. Epiphysis for mammillary process. Atlas. 
9. Epiphysis for transverse process. 26. Posterior arch and lateral masses developed from 
10. Epiphysis for spine. a single centre on either side, which appears 
11. Neuro-central synchondrosis. about 7th week. 
12. Inferior epiphysial plate. 27. Anterior arch and portion of superior articular 
Dorsal vertebra: surface developed from single or double centre, 
13. Centre for body. appearing during Ist year. 
‘14. Superior epiphysial plate, appears about puberty ; 
unites at 25th year. 
15. Neuro-central synchondrosis does not ossify till 
5th or 6th year. 
16. Appears at puberty ; unites at 25th year. 
17. Appears at puberty ; unites at 25th year. 
18. Appears about 6th week. 
Dorsal vertebra. 
28. Epiphysis for transverse process ; appears about 
* puberty, unites about 25th year. 
29, Epiphysis appears about puberty ; unites about 
25th or 27th year. 
30. Centre for body on either side of neural arch ; 
appears about 6th or 7th week, the laminz unite 
Axis, from birth to 15th month. 
19. Centre for transverse process and neural arch; 31. Centre for body ; appears about 6th week, unites 
appears about 8th month. with neural arch from 5th to 6th year. 
neural arch on either side. These commence first to ossify in the upper cervical region 
and extend rapidly downwards throughout the column. They first appear near the bases 
