Freiburger historische Bestände - digital

Dr. Cunningham—Surface Anatomy of the Primate Cerebrum. 297

limbs of the Sylvian fissure. The so-called anterior Sylvian limb, is
merely the anterior free border of the fronto-parietal operculum.

The fronto-orbital sulcus in the anthropoid brain is the representative
of the anterior limiting sulcus of the insula in the human brain. A true
anterior limb of the Sylvian fissure could only be formed in the anthropoid
cerebrum by the backward growth of the anterior lip of this sulcus in the
form of an operculum, and the contact of this with the anterior free
border of the fronto-parietal operculum. By such a proceeding the

Fig. 71.—Lateral view of the left hemisphere of a female foetus in the early part of the eighth month
of development. Drawn hy the American apparatus for tracing orthogonal projections
of the skull.

r. . . Fissure of Rolando.

p. c. s. . Sulcus prsecentralis superior.

p. c. i. . Sulcus prsecentralis inferior.

h. . . Ramus horizontalis.

f.1 . . Sulcus frontalis superior.

f.% . . Sulcus frontalis inferior.

/. m. . Sulcus frontalis medius.

s. . . Single anterior limh of Sylvian fissure.

portion of brain cortex between the anterior free border of the frontoparietal
operculum and the fronto-orbital sulcus, or, in other words, the
exposed part of the insula in the anthropoid brain would become submerged
as in man.

In our study of this question we should not compare the anthropoid
cerebrum with the adult cerebrum of man, but with cerebral hemispheres
of foetuses of the eighth and ninth months of development. At this

ROYAL IRISH ACADEMY.-CUNNINGHAM MEMOIRS, NO. VII. [38]