The sixth vertebra is distinguished from the foregoing by the very great development
of the inferior transverse process, which is directed forwards and outwards
with a slight upward curve. I t is a rounded rod-like structure, separated by a
deep oval notch from the superior transverse process, the length of which it
equals. I t arises from the lower half of the centrum, and the left is shorter than
the right. The pedicles of the neural arch are better developed in this than in any
of the preceding vertebrae. The zygapophyses of the left side, unlike those of the
preceding vertebrae, are nearly on the same plane and are not separated by a notch,
and the conjoint, antero-posterior expansion of the-two is considerably in excess of
that of the right zygapophyses, which are disunited externally by a small notch,
almost converted into a canal by the approximation of the posterior and anterior
extremities of the borders of the facets. The superior transverse process is also
rod-like with a smaller extremity and one directed outwards and forwards. The
neural canal partakes of the same asymmetry that distinguishes the preceding
vertebrae, hut even in a more marked degree, the left having considerably greater
capacity than the right half. The arch is strong but backwardly twisted on the
left side. There is a faint ridge in place of a spinous process, and a small process
on the hinder border of the lamina. The centrum is thicker antero-posteriorly
than in the three preceding vertebrae, hut its articular surfaces are similar to those
in the fourth and fifth.
The seventh cervical is distinguished by its well-developed pedicles, falcate
spinous process, and well developed transverse processes. The body is thicker than
in the. sixth vertebra, and its articular surfaces are transversely oblong. Its under
surface is marked by a longitudinal furrow perforated by a distinctly defined foramen.
The neural canal is triangular, very slightly broader than high. The neural
arch is twisted obliquely from side to side, the right being broader than the left half
and anterior to it. The spinous process is as high as the length of one of the laminae.
I t is directed backwards with a slight twist to the left. The zygapophyses are quite
separate with the facets on the same plane. The transverse process arches outwards,
slightly backwards, and is faintly curved downwards, especially at its extremity,
above which it is marked by a roughened nodosity. At the base of the transverse
process anteriorly occurs the irregular rough surface to which the head of the first
rib is articulated.
Dorsal vertebrce.—The first dorsal vertebra is distinguished by its sharp pointed,
almost falcate-like spinous process, whereas in all the other dorsal vertebrae
this process is abruptly truncated at its extremity.. The first four vertebrae differ,
from the rest of the dorsal segments, by having their transverse processes home by
the. pedicles and by the absence of metapophyses.. Their transverse processes
decrease in size, and the vertebrae in lateral expansion, by the gradual shortening of
the neural laminae, and the processes are brought down nearer and nearer to-
the bodies. These latter, however, increase in transverse breadth and anteroposterior
thickness from before backwards. The laminae also become much reduced
in transverse expansion from the first to the fourth dorsal, and in the latter the«
posterior zygapophyses are close to the base of the spinous process, their facets looking
outwards and very slightly downwards. The spinous processes of the first are higher
than any of the other dorsal vertebrae, and they have a considerable backward course
and are closely opposed to each other. The third is generally distinguished by its
anterior superior angle being projected forwards and upwards in a recurved manner.
The transverse breadth of the bodies increases from the first to the fourth, the vertical
height diminishing, so that the posterior articular surface of the fourth dorsal is transversely
oval; whereas the.anterior surface of the first is quadrangular, but a very little
broader than high. The under surfaces of the body of the first three are marked
by a more or less distinct longitudinal furrow as in the last cervical. On the second,
third, and fourth there is a distinct tubercular swelling where the head of the rib rests
on the posterior margin of the bodies of the vertebrae. The articular surfaces
on the transverse processes are large and longitudinally elongate, and in the first
distinctly concave.
The distinctive features of the six remaining dorsal vertebrae are the presence
of strong metapophyses, short transverse processes, and broad spinous processes
directed forwards, except in the case of the fifth and sixth, which have a slight backward
course. In the fifth, the transverse process is so shortened that it appears merely
as an elongated oval facet on the thickened external surface of the metapophysis,
the thickening itself being the true transverse process which is obscured by the
former. On the sixth, the transverse process attains its least development and
appears as a small expanded ridge. There is a rough surface at its inferior margin to
which the head of the rib is articulated, and a similar and larger surface on the
external posterior margin of the body. Erom the seventh to the ninth vertebrae, the
transverse processes increase very little in size, but become lower and lower in position.
In the tenth vertebra, the rib is suddenly transferred to a transverse process as
long as the centrum, but compressed from above downwards. The metapophyses
become higher and higher in their position as they are traced backwards, and the
zygapophyses in the last dorsal become placed at the base of the spinous process,
the posterior pair having a more and more outward aspect and the anterior looking
directly inwards. The metapophyses are thick powerful processes directed forwards,
upwards, and outwards. The spinous processes increase in antero-posterior
expansion from the seventh to the tenth, the last being much the broadest and higher
than those before it- The last four dorsal vertebrae have their spinous processes
curved forwards. The bodies are all broad and long with a transversely oval section,
and on the under surface they are concave from before backwards but transversely
curved between the transverse processes. The neural canal in the tenth is
broader than high, but its capacity is less than one-half of the canal in the first
dorsal.
Lumbar vertebrce.—The seven or eight, as the case may be, are distinguished by
their .enormously developed transverse processes which attain their maximum in
the third, fourth, and fifth, hut at the same time these processes occur strongly
developed along the first half of the caudal region. The zygapophyses wholly dis