96 STUDY OF A HUMAN SP1NA BIFIDA MONSTER WITH 



In our specimen the pars basalis of the occiput is oval and asymmetrical along 

 its inferior margin, as shown in figure 11, and measures 18 by 14 mm. Its sphe- 

 noidal margin is 6 mm. thick, and the thickness of the bone elsewhere is 3 mm. Its 

 posterior surface is slightly concave, there being a rather deeper depression imme- 

 diately under the sphenoidal articulation than elsewhere. The anterior surface of 

 the pars basalis is nearly flat. The inferior margin has a notch near the midline 

 and on either side of this the bone projects downward, 2 mm. on the right and 4 

 mm. on the left. A slit-like foramen 2.7 mm. wide directed forward and upward 

 pierces the pars basalis near its center. On each temporal bone the eminentia 

 arcuata is very prominent and the fossa subarcuata deeply depressed below. The 

 ear ossicles are well developed and the other relations of the bone are normal. 

 With the exception of the small size of the cranial vault the rest of the skull is well 

 formed. 



The bodies of all the cervical and thoracic vertebrae and the dorsal surface of 

 the first lumbar vertebra are fused together in a bent and irregular central plate 

 of cartilage containing irregular ossification centers. The roots of the arches and 

 the ribs project from this plate. The relations of the various parts are shown in 

 figures 10, 11, and 15. At the superior end of this plate the foveal surfaces of the 

 atlas and its transverse processes are distinguishable, but, as may be seen in figure 

 10, both posterior and anterior arches are lost. The fovese are shifted to the right 

 in relation to their transverse processes, as may be seen in figure 11. This shift- 

 ing causes the right atlantal transverse process to lie immediately under the fovea. 

 The left is uncovered by the fovea on that side, but is fused at its tip with the left 

 pars lateralis. 



Viewed from the side in figure 12, the cervical and lower thoracic portions of 

 the central vertebral plate form the two arms of a wide-mouthed U, while the 

 bent base of the U occurs in the plate from the level of the first to the sixth ribs. 

 Besides this marked lordosis, there is a very slight lateral bend which shows in 

 the dorsal view of the skeleton (fig. 10), giving the vertebral plate a slightly curved 

 S-shape. (This condition of scolisosis and lordosis in varying degrees is very 

 frequently noted in the extreme forms of spina bifida.) The concavity at the right 

 margin of the vertebral plate is opposite the first rib and at the left opposite the 

 sixth rib. From the central plate of this specimen throughout its extent the radices 

 project outward on both sides and formed between them are two uneven rows of 

 intervertebral foramina. The processes are tiny spicules of bone in the cervical 

 and upper thoracic region, becoming larger in the lower part of the column. In 

 the cervical region 7 radices are distinct and 12 in the thoracic region. The former 

 could not all be shown in the drawings. 



The arches of both cervical and thoracic regions are everted and fused. This 

 formation, together with the antero-posterior bend of the plate, makes a rather 

 deep pocket of bone which contains parts of the much disturbed central nervous 

 system. The lumbar and sacral vertebral column is much less affected than the 

 upper part. The dorsal part of the first lumbar vertebral body is fused with the 

 thoracic vertebrae, its ventral surface, however, being distinct. The four lower 



