72 THE OSTEOLOGY AND MYOLOGY 



The back can be greatly hunched up, and the root of the neck brought into line with 

 the pelvis. The " centre of motion " is at the last three dorsals and first lumbar, as 

 shown by the verticality of the spines of these vertebrae. The spines of the several 

 anterior dorsals are much inclined baclcward, in order to allow the abrupt upward curve 

 of the cervicals in the usual position of the body. Great length of spine is necessary 

 in these vertebras, to allow of advantageous attachment of the muscles situated in the 

 concavity of the S. The occasion for the great expansion of the transverse process 

 of the sixth cervical is seen when the neck-bones are placed in slfu with the dorsals. 

 This cervical is at the point of greatest convexity of the S; its processes form prominent 

 points d'apjiui for muscles upon the anterior aspect of the spinal column. 



As I have said, the transition from the cervical to the dorsal series of vertebrte is abrupt, 

 and this occurs, both from the configuration of the two contiguous bones themselves, and 

 the direction of the two series of bones. The large cervical spinous processes almost dis- 

 appear with the last of that series, to suddenly reappear upon the first dorsal, but with 

 different shape. The spine of the first dorsal is a long, slendei-, tapering process, directed 

 a little obliquely backwai'd ; but in spite of this backward direction, so sharp is the angle 

 between the neck aiid back, that the spine, in some attitudes, may reach forward so that 

 its apex almost touches that of the fifth cervical — overreaching the sixth, and more espe- 

 cially the seventh cervical. The dorsal spines increase in length and obliquity of direc- 

 tion to the third vertebra, after which they begin to shorten and to stand more upright. 

 The occasion for their greatly attenuated form is found in the fact that they project into 

 the cavity of the sigmoid curve that the back here makes, and must therefore be capable 

 of being packed in less space, else this concavity would not be attainable. Their slender 

 spinous figure is preserved to the sixth, where they begin to thicken, and have, on this and 

 two or three succeeding vertebrse, somewhat the massive pillar-like figure of those of the 

 middle cervicals. They are thickened, widened and shortened on succeeding vertebrae, 

 until the last has little or nothing to distinguish it from a lumbar spine. In this and in 

 all other featui'es the last dorsal is so much like the first lumbar that its being costiferous 

 is almost its sole peculiarity. 



The transverse process of the first dorsal is like that of the last cervical, but much 

 stouter, and bears upon its apex a very distinct facet for the rib. This process grows 

 shorter with successive vertebrie, and only retains the same general physical character as 

 far as the eighth, beyond which it begins to be subjected to the modification of fonn that 

 culminates in the lumbar series. There is a corresponding modification in the vertebral 

 extremity of the ribs, which no longer articulate witli the spine by their " tubercles " ; in 

 fact it is hardly possible to recognize "head, neck and tul)ercle," on ribs behind the eighth 

 pair. As will be seen presently, the transverse processes of the lumbar vertebrae are ex- 

 panded and mutually overlapping, almost exactly as in the cervical series. Something of 

 this obliquity and longitudinal expansion is the modification that the transverse processes 

 of the five posterior dorsals undei-go ; but the development is not sufficient to produce 

 decided overlapping. Coincidently with this modification of the diapophysial elements, 

 metapophyses began to be developed, increase in size to the last dorsal, and thence con- 

 tinue into the lumbar region. The articulations of the anterior dorsal lie directly in the 

 axis of the spine, the articular facets of the pre-zygapophyses looking upward, and those 

 of the post-zygapophyses downward. With succeeding vertebrae, obliquity, both in a 



