Freiburger historische Bestände - digital

164

Cunningham Memoirs.

These results are very different from those which have been obtained
by either Benedikt or Giacomini. The first of these authorities, in thirty-
eight hemispheres found a complete connexion between the Rolandic fissure
and the Sylvian fissure in eighteen cases, and an incomplete connexion in
other six.* Giacomini,f on the other hand, examined 336 hemispheres, and
in only 21 of these was the communication present.

Eberstaller gives us what appears to me to be the true explanation of
this occasional communication between the fissure of Rolando and the
fissure of Sylvius. He points out that in most hemispheres a small variable
tertiary furrow may be detected upon the margin of the fronto-parietal
operculum below the lower end of the Rolandic fissure. To this he gives
the name of the inferior transverse furrow of the fissure of Rolando. It
takes an oblique course upwards and forwards, and is usually separated
from the under end of the fissure of Rolando by a superficial gyrus which
connects the two central convolutions. Sometimes, however, the fissure of
Rolando opens into the inferior transverse furrow, and in such cases the
latter may appear as a transverse termination to the main furrow; or
should the inferior transverse furrow be in connexion with the Sylvian
fissure, which it most frequently is, a direct but superficial communication
between the Rolandic and Sylvian fissures is established. In either case,
if the lips of the fissure of Rolando in its lower part be separated from each
other, the superficial gyrus which intervenes between the two sulci under
ordinary circumstances will be observed pressed down into the bottom.
This marks the lower limit of the normal fissure of Rolando. Its shallow
onward prolongation into the Sylvian fissure, or the transverse terminal
branch, as the case may be, is in reality an additional element—the inferior
transverse sulcus of Eberstaller. These facts I can verify in every
particular.

The connexion between the fissure of Rolando and the inferior transverse
sulcus is of late occurrence. In only one full-time foetal hemisphere
have I noticed it, and even here the annectant gyrus was barely

* Anatoniische Studien an Verbrecher-Gehirnen, p. 96. Wien, 1872.
f Varieta delle circonvoluzioni cerebrali dell' uomo. Torino, 1882.