Freiburger historische Bestände - digital

Mr. Victor Horsley—Cranio-Cerebral Topography.

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also defines the level and locality of the anterior perforated spot, the optic
chiasm a, and the origin of the middle cerebral artery.

Viewed from the front, the chiasma in the adult extends for about 7 mm.
on each side of the middle line, i.e. about one-fifth of the breadth of the
hemisphere ; closely outside it and in front lies the anterior perforated spot,
the outer limit of which corresponds with a plane parallel to the mesial
plane of the skull, and passing through the middle of the superior orbital
margin.

Beyond this plane, and between it and the external or temporal surface
of the skull lies the commencement of the Sylvian fossa.

The anterior surface or aspect of the temporal lobe includes the small
portion lying in front of the lateral border of the hemisphere (yid. sup.) and
which is made up of the anterior extremities of the superior middle and
inferior temporal gyri, and also of the anterior surface of the uncinate gyrus.
Each of these components forms about half of the surface in question, but
the uncinate portion lies much further back than what is commonly regarded
as the tip of the lobe. In fact, whereas the anterior extremity of the tip of
the temporal lobe lies in a vertical* plane passing through the junction of
the middle and posterior thirds of the (breadth of the) great wing of the
sphenoid, i.e. projecting under the small wing (according to Fere' it reaches
10 to 15 mm.), the plane of the tip of the uncinate gyrus only lies as far
forwards as a vertical* plane through the foot of the vertical stem of the
prsecentral sulcus, or at least the oblique sulcus.

The lateral surface of the temporal lobe requires no notice here, as its
borders have been described, and the individual gyri and sulci are alluded
to further on.

The inferior surface of the temporal lobe is limited anteriorly by a line
prolonging the lateral margin of the hemisphere to the middle line across
the lobe and posteriorly by the parieto-occipital notch. Its middle presents
the shallow fossa which is the extension of the notch on the lateral margin,
and which coincides with the petrosal elevation. In front of this " petrosal"
fossa, the anterior third of the inferior temporal gyrus and a small portion

* /. e. at right angles to the middle plane of the head.

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