By some it is considered a
reversion to the lower species, while others deny this and claim
it to be simply a pathologic appendix.
Anomalies of the Spinal Canal and Contents.--When there is a
default in the spinal column, the vice of conformation is called
spina bifida. This is of two classes: first, a simple opening in
the vertebral canal, and, second, a large cleft sufficient to
allow the egress of spinal membranes and substance. Figure 130
represents a large congenital sacral tumor.
Achard speaks of partial duplication of the central canal of the
spinal cord. De Cecco reports a singular case of duplication of
the lumbar segment of the spinal cord. Wagner speaks of
duplication of a portion of the spinal cord.
Foot records a case of amyelia, or absence of the spinal cord, in
a fetus with hernia cerebri and complete fissure of the spinal
column. Nicoll and Arnold describe an anencephalous fetus with
absence of spinal marrow; and Smith also records the birth of an
amyelitic fetus.
In some persons there are exaggerated curvatures of the spine.
The first of these curvatures is called kyphosis, in which the
curvature is posterior; second, lordosis, in which the curvature
is anterior; third, scoliosis, in which it is lateral, to the
right or left.
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