The complete fissures of the human cerebrum, and their significance in connection with the growth of the hemisphere and the appearance of the occipital lobe / by D.J. Cunningham.

  • Cunningham, D. J. (Daniel John), 1850-1909.
Date:
[1890?]
Catalogue details

Licence: Public Domain Mark

Credit: The complete fissures of the human cerebrum, and their significance in connection with the growth of the hemisphere and the appearance of the occipital lobe / by D.J. Cunningham. 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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    spheres examined, although it was not, in every case, continued round the occipital pole into the precursor of the calcarine fissure on the medial face of the cerebrum (figs. 2, 4, and 5, E.C.). In figure 4 (No. 1) the left hemisphere of an embryo at about the eleventh week is represented. Two short fissures— one in front and the other behind—are alone present on the outer surface of the cerebrum. Between these, however, the cerebral mantle is faintly streaked by a series of faint grooves, which present very much the direction of the transitory fissures when fully developed. Most likely these markings indicate the initial stages in the formation of the fissures. When fully formed, a deep infolding is the result. Figure 3 (b.) shows a transverse microscopical section through the middle of the fissure indicated in the frontal region of the brain depicted in figure 2, No. 3, G. The lips of the furrow are closely applied to each other at the surface, and it is this that gives to such fissures their sharply-cut linear appearance; but, towards the bottom of the sulcus, the walls of the fold are separated to a .small extent, and a slight recess is formed between them. Schmidt has stated that, at the places where the bending-in of the cerebral wall takes place, the wall of the hemisphere is thinner than elsewhere. This is well seen in figure 3 (b.), although on the one side of the fissure it is better marked than on the other. At the same time it must be noted that this condition is not universally present. In the shallow parts of a fissure, or where a fissure is shallow throughout, it is the bottom of the fold that becomes thinned (fig. 3, A. and c). When a continuous series of sections is made through the entire length of one of the transitory fissures the central part is seen to be very deep (fig. 3, B.), while at its two extremities it is shallow, and the bottom gradually rises to the surface (fig. 3, A.). The folds, therefore, as seen from the ventricular aspect, present a semilunar form (fig. 2, No. 3, G.). A .study of the various specimens would seem to indicate that the process of obliteration consists in a shortening of the fissure from both extremities towards the centre. More and more of the bottom of the furrow rises to the surface, until at last the deep central part alone remains in the form of a round knob-like elevation on the ventricular aspect of the wall (fig. 10, Nos. 3 and