Freiburger historische Bestände - digital

348

Cunningham Memoirs.

uncertain. (See Riidinger, and cf. Professor Cunningham's remarks, p. 236.)
It may be said that at the commencement of its course it lies midway
between the longitudinal and Sylvian fissures respectively; but it runs
upwards and inwards so as to pass at a near distance the outer end of
the external parieto-occipital fissure.

For the length of this latter we have no reliable data, and therefore
must assume it arbitrarily to vary in man from 1 to 2 cm. in length.
Although such absolute figures are almost useless, they are in this particular
the only facts before us.

Thus the supramarginal gyrus underlies almost exactly the centre of
the parietal eminence. The special observations of Fere* in this particular
are confirmed in general by all who have explored this region. The same
topographical localization naturally gives the posterior extremity of the
superior temporal gyrus (q. v.).

The topography of the inferior parietal lobule is so far easy that it
simply consists of the supramarginal gyrus with the sub-divisions of the
same, such as are produced by the branches of the sagittal portion of the
intraparietal sulcus. The lower margin is, of course, fixed by the determination
of the site of the posterior limb of the fissure of Sylvius. It is,
however, very difficult in the absence of minuter investigation than at
present exists to express the situation of the angular gyrus with real
accuracy.

The Calloso-marginal Sulcus.—The localization of the situation of the
calloso-marginal sulcus in the entire head is simplified in so far as that it
lies close to the middle line. Anteriorly its limit bisects the distance
between the frontal pole of the hemisphere and the rostrum of the
corpus callosum. This latter point has been observed by Altoukhoff
alone.

Posteriorly the calloso-marginal sulcus rises when opposite the level of
the point where the fissure of Rolando cuts the margin of the hemisphere
and joins the same edge midway between the fissure of Rolando and the
parieto-occipital fissure. It thus limits postero-inferiorly the representation
of the lower limb on the inner surface of the hemisphere.

Corresponding with its extremities is naturally the extent of the major