The Sylvian fissure and the island of Reil in the human brain / by D.J. Cunningham.

  • Cunningham, D. J. (Daniel John), 1850-1909.
Date:
[1891?]
Catalogue details

Licence: Public Domain Mark

Credit: The Sylvian fissure and the island of Reil in the human brain / 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.

    8/10 (page 290)
    of growth, it has been supposed that, in addition to the marked changes which occur in the position of the suture itself, there is a slipping round of a portion of the outer surface of the temporal lobe so as to take up a position on the base of the cranium coincident with the marked expansion of the cranial floor of the young skull. In other words, that the infero-lateral border of the hemisphere becomes more elevated at the expense of the outer surface of the temporal lobe. This is a highly ingenious theory, and at first I was inclined to accept it; but, as my investigation advanced, I saw that it was untenable, and for this reason, that throughout all periods of growth the'same sulci and the same convolutions of the temporal lobe lie between the Sylvian fissure above and the infero-lateral border of the hemisphere below. The growth-change in the position of the suture is very marked. At first the squamo-zygomatic bone is low and does not override the lower border of the parietal, but, as growth advances, it extends more rapidly than the parietal bone, and ascends so as to overlap it to a considerable extent. The sutural line is always regarded as coinciding with the upper border of the squamous bone. The proportion of cranial vault above and below the suture line in the adult is 75-25, whilst in the last month of foetal life it is 81-7-18-3. But great as this growth-change is, it is more than equalled by that in the position of the Sylvian fissure on the surface of the hemisphere. The fissure descends rapidly during infancy and early childhood, so as to increase the depth of the parietal lobe and diminish that of the temporal lobe. The following are Parietal Depth. Temporal Depth. Adults, . 69-1 30-9 From 11 to 15 years, . 69-1 309 From 4 to 5 years,. . . 65-7 343 First year of life, . 63-9 36-1 Full-time foetuses, . 61-6 38-4 7 J to 8J month foetuses . 61 390 There is apparently no difference in this growth-change between the male and the female, but the left hemisphere lags slightly behind the right hemisphere all through.