The Bradshaw lecture on the brain structures concerned in vision and the visual field : delivered before the Royal College of Surgeons of England on December 11th, 1909 / by Francis Richardson Cross.

  • Cross, Francis Richardson.
Date:
1909
Catalogue details

Licence: In copyright

Credit: The Bradshaw lecture on the brain structures concerned in vision and the visual field : delivered before the Royal College of Surgeons of England on December 11th, 1909 / by Francis Richardson Cross. Source: Wellcome Collection.

Provider: This material has been provided by Royal College of Physicians, London. The original may be consulted at Royal College of Physicians, London.

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    I have seen a narrowing of the nasal fields which I have taken to be due to some error in the anterior perforated space. Acromegaly seems undoubtedly to depend on a diseased condition of the pituitary body, and the close relationship of the latter with the chiasma accounts for the early onset of bitemporal hemianopsia. Conditions of hemianopsia due to imphcation of the chiasma may, however, be very marked without any symptoms of acromegaly, and therefore presumably without imphcation of the pituitary body. The fibres in the chiasma are decussating, direct, and intercerebral. Special interretinal fibres probably do not exist. The intercerebral are not found in the optic nerve ; they join together the two medial geniculate bodies as the commissure of Gudden, which can be separated from the optic chiasma, and are probably concerned with the sense of hearing. In all vertebrata below mammals, and in some higher mammals, the optic nerve fibres are said all to decussate in the chiasma. In the higher mammals and in man the decussation is certainly incomplete. A portion of fibres pass direct from the temporal side of the retina to the same side of the brain. The more perfect the degree of binocular vision the larger the bundle of direct fibres. In man the decussating fibres are about three-fifths of the whole, the other two-fifths pass directly from the temporal retina to the same side of the brain. The chiasma is connected with the brain by the optic tracts. They wind round the cerebral peduncles, each dividing into a medial and lateral root.