Freiburger historische Bestände - digital

264

Cunningham Memoirs.

little sulcus in 27'8 per cent, of the hemispheres examined, although in
certain of these it was broken up into two short, more or less transverse
depressions.

The main portion of the furrow may be continuous and uninterrupted
throughout (27*8 per cent.); much more frequently it is broken up into
two (49-2 per cent.) or three pieces (23 per cent.) by deep or superficial
annectant gyri, which pass between the superior and middle frontal gyri.

When the interrupting gyri are on the surface the separate pieces of
the furrow succeed each other, as a rule, in a very definite manner. In
direction they are oblique, and the posterior end of each is placed on the
outer side of the anterior extremity of the one behind, whilst the other
extremity approaches close to the mesial border of the hemisphere.
Eberstaller has also observed this mode of arrangement of the separate
pieces of the first frontal furrow in those cases where its continuity is
disturbed by the presence of superficial annectant gyri.

In the negro cerebrum this furrow appears to have a greater tendency
to break up into separate parts than in the European.

VII. The Sulcus Frontalis Medius. Eberstaller* has the credit of
having first clearly recognized and described this fissure, although it would
seem that it was also independently identified as a distinct fissural integer
by Herve\t It is one of great interest, but in the hands of these
two authors it has been assigned, as we shall see later on, an altogether
undue importance.

The sulcus frontalis medius traverses the middle frontal convolution in
an antero-posterior direction, so as to divide it into an upper and lower
portion. Eberstaller describes the furrow in the following terms :—" In
its typical form the middle frontal furrow appears generally as a sagittally
directed sulcus, which begins in a transversely placed short branch,
midway between the anterior central convolution and the orbital
border, and ends in a similar transverse branch immediately above

* TJeber Gehirnwindungen.—Oesterreichische aerztliche Yereinszeitung, No. 8, 1884 ; also
Das Stirnliirn, p. 72. Leipzig, 1890.

f La circonvolution de Broca. Paris, 1888.