Freiburger historische Bestände - digital

Me. Victoe Hoesley—Cranio-Cerebral Topography.

341

Sulcus Frontalis Superior vel Primus.—This, the superior frontal sulcus
of most authors, possesses a very important topographical significance,
because the level it forms (see Introduction), if continued backwards, is a
very valuable dividing line morphologically, since it separates the representation
of the respective limbs. Its line is nearly parallel to the contour of
the hemisphere, trending inwards anteriorly, and terminates posteriorly
in the centre of the sulcus postcentralis superior. The projection of this
sulcus is easy so far as its vertical depth is concerned, since it lies intermediately
between the margin of the hemisphere and the inferior genu of
the fissure of Rolando. Antero-posteriorly, it becomes very important to
determine the point of junction of the superior frontal with the superior
prsecentral sulcus. From examination of the series of casts in the Broca
Museum I found that in 18 the position of this point was as follows :—In
10, it was midway between the coronal suture and the fissure of Rolando ;
in 3, at the junction of the anterior two-thirds and posterior third of the
interval; in 3, at the junction of the anterior three-fifths and posterior
two-fifths; and in 2, just posterior to the centre of the interval in question.

From these observations it is clear that the point is a constant one,
and varies between midway and the junction of the two hinder thirds, i. e.
within limits of about 1 cm. of absolute length. Examination of Professor
Cunningham's preparations shows the same relations to exist.

Age does not seem to play a noteworthy influence in this measurement,
the ages of the above varying from one month to 71 years, without
concomitant and regular variation of the proportional distance. However,
it is to be noted that in measuring the interval in an infant the bregmatic
extremity of the coronal suture must be taken, by continuing the direction
of the bony union ; otherwise, if the edge of the bone bounding the
lozenge-shaped space be taken as the starting-point, the distance obtained
will be curtailed anteriorly.

The topography of the anterior three-fourths of the superior frontal
sulcus has at the present time no particular import; we may therefore
pass on to the next sulcus.

Sulcus Frontalis Inferior vel Secundus.—By reason of this sulcus bordering
the upper limit of the classical third frontal gyrus it has acquired