On the posterior lobes of the cerebrum of the quadrumana / by William Henry Flower ; communicated by Dr. Sharpey.

  • William Henry Flower
Date:
[1862]
Catalogue details

Licence: Public Domain Mark

Credit: On the posterior lobes of the cerebrum of the quadrumana / by William Henry Flower ; communicated by Dr. Sharpey. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    removed with the saw and bone forceps, then the dura mater was taken away, and the contents of the cranial cavity exposed. While still in an undisturbed condition, the extent to which the posterior lobes of the cerebrum projected beyond the cerebellum was ascertained to be fully ^th of an inch. On comparing the form of the brain with that of the human subject, very great similarity is seen in the contour of the posterior half of the cerebrum, but the anterior lobes in the Monkey are much reduced, being narrowed almost to a point, flattened, and largely excavated in the orbital regions. Fig. 6 (Plate III.) is a proflle ■view of this brain, and shows accurately the relative form and situation of the different parts while in situ, and the arrangement of the sulci upon the outer face of the hemisphere. Fig. 3 (Plate II.) is a sketch of the convolutions of the inner face of the right hemi- sphere. The calcarine sulcus is very strongly marked, and describes a curve having the concavity upwards; it bifurcates as usual at the posterior end. The occipito-parietal sulcus, instead of running do^wnwards and forwards as in Man and Presbytes, is directed somewhat backwards, and does not join the calcarine sulcus,-but terminates at the upper margin of a prominent gyrus (the second internal annectent) which borders the last- named fissure superiorly. The sections show that the calcarine fissure extends to a greater depth than in any other genus (yet examined), and has a singular complexity of form, as there is concealed within it, and attached to its floor, a small but distinct gyrus (Plate II. fig. 3, and Plate III. fig. 7, 26). This convolution, which may be called from its position “ calcarine,” commences anteriorly by a slight elevation of the floor of the calcarme fissure, increases as it proceeds backwards, and comes to the surface where the sulcus turns up towards its termination; then, bounded superiorly by the lower branch of the sulcus, sweeps round the inferior border of the lobe, and becomes continuous ■with the infero-occipital gyrus of the outer side. It appears to be always present in CercopitJiecus, Macacus, and Cehus, and probably in all the allied genera, but is absent in the highest and lowest members of the order. The consequence of the depth and complexity of the calcarine sulcus is that the involution of grey matter forming its walls is much increased, and bears a very large proportion to the mass of the lobe, and the cornu of the ventricle is thro'wn quite to the outer side of the hemisphere, being at its termination only separated by a thin stratum of white matter from the cortical layer of its external face. The walls of the comu are in such close apposition that I have not been able to satisfy myself that it is in the adult Cei'co])itJiecus an actual cavity in the same sense as the remaining portion of the ventricle, especially as the staining of the lining membrane found in other parts rarely extends more than a quarter of an inch upon the surface of the hippocampus minor. But as fine sections of hardened brains show a line in which the cerebral substance is absent, having always the same definite extent, form, and direction,—as the slightest touch with the handle of the scalpel will separate the walls,—as in some genera it is undoubtedly as distinctly open as any other part of the cavity, and as it has been so considered by Geatiolet, Huxley, and other competent observers, I have no hesitation in looking upon it as homologous to the posterior cornu