File:Wheeler-plate03.jpg

Plate 3

Fig. 12. The left-hand view of the axial skeleton

with subdural cast in place and median outline of specimen given. This figure shows the extreme dorsoflexion of the vertebral colunm. The occiput is in position and its squamosal junction on the left with the second lumbar arch is shown. The origin of the spicule of bone which projects out from the transverse process in the thoracic region is visible. The crowding and irregular arrangement of the fifth to the ninth ribs is shown.

Fig. 13. The superior view of the occipital bone

shown with its enlarged foramen magnum. A normal-sized foramen is designated by a dotted line. The left jugular process is prominent when compared with the right, which seems to have been twisted over to the side. The anterior outlet to the right hypoglossal canal is shown with the tiny rod of bone which divides the exit of the hypoglossal foramen on the right side immediately under it.

Fig, 14. The inferior surface of the occipital bone shows the large foramen

On the squamosal surface the exostoies which join the lumbar vertebra show. On the partes laterales the condylar surfaces and on the left side the cartilaginous process which joins the transverse process of the atlas may be seen. The notched basal margin of the basiocciput also is visible. (Natural size).

Fig. 15. This shows schematically the ventral surface of the thoracic vertebral plate

with pairing of the origin of the seventh and eighth and ninth and tenth ribs on the right side, and of the first and second, and the third and fourth on the left.

Fig. 16. This shows schematically the sternum with six costal cartilage attachments on each side

The last attachment on both sides is that of the seventh rib. The discrepancy occurs through the second rib becoming aborted on the right side, and the sixth being aborted on the left side. There are four centers of ossification on the midUne of the sternum. The upper two arc opposite the first costal cartilage and resemble an exclamation mark. The lower two are oval (4 by 3 mm.), with long diameter perpendicular. One is about at the middle point of the sternum and the other 1 cm. below it an episternum surmounts the sternum and the xyphoid process projects at its inferior end.