. Journal of anatomy . y further forward than the arcuate sulcus did; but theforward reach of the arcuate sulcus in apes shows as great individualvariations as that of the superior frontal sulcus in man. In the presentcase the superior frontal sulcus runs much further forward in the righthemisphere than in the left. Probably this extreme anterior part has less Some Morphological Aspects of Microceplialic Idiocy 329 morphological significance than the part which we have seen traversing thearea tor eye-movements. The only part of the fronto-marginal sulcus to which in this case theterm sulcus tr
. Journal of anatomy . y further forward than the arcuate sulcus did; but theforward reach of the arcuate sulcus in apes shows as great individualvariations as that of the superior frontal sulcus in man. In the presentcase the superior frontal sulcus runs much further forward in the righthemisphere than in the left. Probably this extreme anterior part has less Some Morphological Aspects of Microceplialic Idiocy 329 morphological significance than the part which we have seen traversing thearea tor eye-movements. The only part of the fronto-marginal sulcus to which in this case theterm sulcus transversus anterior can be properly applied is the lateralbranch. Ihis is seen in the gorilla, running outwards and backwards asliort distance towards the fronto-orbital sulcus in a direction pointino- wellbelow the upper extremity of that sulcus. In this microcephalic Tdiotsbrain the lateral branch is remarkable for its great length, simplicity, andstraightness; it extends without interruption nearly to the edge of the. Fig. 6.—Antero-lateral aspect of the right hemisphere. orbital operculum. If we compare this brain with that of a gorilla weobserve, on looking at it from the front, that the stem of the fronto-marginal sulcus occupies almost exactly the same position as in the gorilla,but the lateral branch is very much longer, and we see that the changeswhich have led to the formation of an orbital operculum in the humanspecies are referable to a growth which has taken place external to thesulcus rectus. In these changes the lateral branch has played animportant part. If we mark out the course of this branch upon Flechsigs myelinationdiagram, we see that its inner end, where it arises from the stem of thesulcus fronto-marginalis, lies in a region which is one of the latest tomyelinate in the brain of modern European man (35th in order, accordingto Flechsig). As it passes outwards, it traverses cortex myelinating earlier 880 Dr Sydney J. Cole (28th to 30th in order). And it e
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Keywords: ., bookcentury1800, bookdecade1860, booksubjectanatomy, bookyear1867
