Freiburger historische Bestände - digital

Dr. Cunningham—Surface Anatomy of the Primate Cerebrum. 171

surface, it is true, but it is still to be discerned, even in the adult brain, in
the bottom of the fissure, in that shallowing or deep annectant gyrus which
we have described at the junction of the upper and middle thirds of the
sulcus. In some rare cases, as we have already stated, the two original
portions of the fissure of Rolando remain quite distinct throughout life.
In these the intervening bridge of cortex remains on the surface, and
is not depressed by the fusion of the upper and lower divisions of the
fissure.

Krause* has stated that the fissure of Rolando owes its origin to the
constricting action of a vein which, crossing the surface of the hemisphere,
opens above into the superior longitudinal sinus, whilst below it communicates
with the vena fossae Sylvii. This vein, he considers, fails to
keep pace with the growth of the hemisphere, and consequently cuts into
its surface and produces the fissure of Rolando. He says: "An beiden
Enden blind geschlossen, stent dieser tiefe Sulcus (fissure of Rolando) in
keinerlei Beziehung zu den ubrigen Sulci (und Gyri), die er riicksichtslos
durchkreuzt. Es handelt sich ganz einfach um eine Venen-Verbindung, die,
im 4 monatlichen Fotus leicht injicirbar und hervorstechend entwickelt,
spater im Wachstum zuriickbleibt. Beim Embryo von 14 cm. Lange und
dem angegebenen Alter betragt die Dicke der, noch ehe cler Sulcus centralis
sich einzukerben beginnt, seinen Verlauf markirenden Vene o, 5 mm., beim
6 monatlichen Fotus 1 mm. Es verlauft in dem Sulcus eine V. cerebralis
superior, welche oben in den Sinus sagittalis superior einmundet, unten aber
mit der V. fossae Sylvii communicirt." I must confess that I have been
able to find no confirmation of this view of the origin of the fissure of
Rolando in the foetal brains which I have examined. If the sulcus were
produced by the pressure of a vein the ends of which were tied down at
the fossa Sylvii below, and at the superior margin of the hemisphere above,
it would be the middle portion of the sulcus which would appear first, and
the furrow would elongate in an upward and downward direction from this.
As we have noted, however, it is the lower portion of the furrow which is
first developed, and the upper portion appears later as an independent

* Specielle und macroscopische Anatomie, Hannover, 1879, p. 813.

[22*]