ClipArt ETC
"Ideal plan of the double-ringed body of a vertebrate. N, neural canal; H, haemal canal; the body separating them is the centrum of any vertebra, bearing e, and epapophysis, and y, a hypapophysis; n, n, neurapophyses; d, d, diapophyses; ns, bifid neural spine; pl, pl, pleurapophyses; h, h, haemapophyses; hs, bifid haemal spine. Drawn by Dr. R. W. Shufeldt, USA, After Owen. The Axial Skeleton of a bird or any vertebrated animal, that is, one having a back-bone, exhibits in cross-section two rings or hoops, one above and the other below a central point, like the upper and lower loops of a figure 8. The upper ring is the neural arch, so called because such cylinder encloses a section of the cerebro-spinal axis, or principal nervous system of a vertebrate (brain and spinal cord, whence arise all the nerves of the body, excepting those of the sympathetic nervous system). The lower ring is the haema arch, which similarly contains a section of the principal blood vessals and viscera.

Axial Skeleton

"Ideal plan of the double-ringed body of a vertebrate. N, neural canal; H, haemal canal; the body separating…

"Fig 55. - Actual section of the body in the thoracic region of a bird. N, neural canal; H, haemal canal; c, centrum of a dorsal vertebra; hy, hypapophysis; d, diapophysis; z, zygapophysis; ns, neural spine; r, pleurapophysis, or vertebral part of a free rib, bearing u, uncinate process or epipleura; cr, haemapophyses; or sternal part of the same; st, section of the sternum or breast-bone (haemal spine). Designed by Dr. R. W. Shufeldt, USA. This figure shows such a section, made across the thoracic or chest-region of the trunk. Here the upper ring (neural) is contracted, only surrounding the slender spinal cord, while the lower ring is expanded to enclose the heart and lungs." Elliot Coues, 1884

The Axial Skeleton

"Fig 55. - Actual section of the body in the thoracic region of a bird. N, neural canal; H, haemal canal;…