Biology Reference
In-Depth Information
Figure 23. Brain shape in normal humans compared with microcephalic
humans. Right side of a virtual endocast from a normal man (A), left side of
an actual brain from a 6.5-year-old male microcephalic (B), and left side of a
virtual endocast from an adult microcephalic man (C). Numbers represent cra-
nial capacities (in cm
3
). The underneath surface of the frontal lobes (arrows) is
flatter in the microcephalics than in the normal individual. Notice also that the
cerebellum
(ce)
is large, low, and the most posteriorly protruded structure in
the microcephalics, whereas the occipital pole
(op)
protrudes farthest in normal
humans. Prepared by Kirk Smith, Mallinckrodt Institute of Radiology; photo-
graph of the brain is courtesy of the National Museum of Health and Medi-
cine; reproduced from Falk, Hildebolt, et al., “Brain shape,” 2007.
casts tend to have very narrow frontal lobes that are flattened rather
than rounded on their underneath surfaces, like those of normal indi-
viduals. They also have relatively large cerebella that protrude posteri-
orly compared with the smaller cerebella of normal humans, which are
tucked forward and underneath the occipital lobes.
The next step was to try to quantify these observations and use
