Freiburger historische Bestände - digital

276

Cunningham Memoirs.

stem of the inferior prsecentral sulcus. It is placed above the level of the
anterior part of the same furrow, and its relationship to it is thus obscured.
The condition of the ramus horizontalis is also misleading. It has its
anterior end tilted upwards, so that it almost assumes a vertical direction.

The development of the basal part of the inferior frontal sulcus in
continuity with the inferior prsecentral furrow explains those cases in the
adult in which we have a complete union of the two furrows. When the
basal portion of the furrow is formed independently it may either maintain
its separate condition, or extend backwards and unite superficially with the
inferior prsecentral furrow (p. 255).

Fig, 63.—Lateral view of a foetal cerebrum in the latter part of the seventh month of development.

Drawn by the American apparatus for tracing orthogonal projections of the skull.

r. . . Fissure of Kolando. /.2 . . Sulcus frontalis inferior.

p. c. s. . Sulcus prsecentralis superior. /. m. . . Sulcus frontalis medius.

f.1 . . Sulcus frontalis superior. p. c. i. . Sulcus pracentralis inferior.

h. . . BamUs horizontalis. s.1 . . Single anterior limb of the Sylvian fissure.

But the inferior frontal sulcus does not in every case appear in two
separate pieces. Sometimes, from the very first, it assumes the form of a
sharply-cut linear furrow (PI. i., fig. 24, f?).

In figure 31, Plate i., a very puzzling condition is exhibited, and yet it
is one which is not very rare. I have lettered the fissure in question p. c. i.,
although I can hardly believe that it has much in common with the sulcus
prsecentralis inferior. It seems rather to be an early stage of what is
present in the hemispheres figured in pp. 250 and 251. If this be the case