Galen : two bibliographical demonstrations in the library of the Faculty of Physicians and Surgeons of Glasgow, 9th December, 1891, and 30th March, 1893 / by James Finlayson.

James Finlayson

Date:: 1895

Credit: Galen : two bibliographical demonstrations in the library of the Faculty of Physicians and Surgeons of Glasgow, 9th December, 1891, and 30th March, 1893 / by James Finlayson. 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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$[Optic nerves and commissure.']—Thus the sensitive nerves descend from the encephalon to the eyes {optic nerves), which Herophilus called ducts, for they alone have canals manifest to the sense of sight, which are for the purpose of giving passage to the pneuma ; these nerves not only have this peculiarity which distin- guishes them from other nerves, but, moreover, they arise from different parts of the brain. During their course they are united together, and afterwards divided, being separated from each other. Why, then, has not nature given their superior prolongations a common point of origin 1 Why having created them, the one on the right side and the other on the left, instead of taking them directly into the region of the eyes, has it caused them to curve inwardly, joining them together and uniting their ducts, thereafter causing them to enter the eyes each in the direction of its superior prolonga- tion 1 In a word, instead of transposing them by sending the nerve of the right side to the left eye, and that of the left side to the right eye, nature has given to these nerves a figure very similar to x^. At least, from a careful dissection, one might form the opinion that these nerves are transposed, and that they pass the one over the other. This is not, however, the i-eal state of matters. For after being brought into contact with each other in the cranium so that their ducts are united together, they immediately separate from each other, showing clearly that they are only brought together to effect a junction of their ducts.—(Rendered from Daremberg's Translation : Galien, tome i, pp. G37, 638. Uiilite des parties du corps, X, 12, Kiihn, tom. iii, p. 814). A passage, to which Dr. A. D. Waller directed my attention, serves to show the minuteness with which Galen studied the functions of the nervous centres, and illustrates the method which he pursued by physiological experiments on living animals:— [Effect of transverse sections of whole or half of Spinal Cord.]— Moreover you have seen that transverse incisions of the whole cord deprive all parts of the body below of sensibility and of movement. And you have seen in dissections that transverse incisions of the cord (from right to left or from left to right) which stop at its centre, do not paralyse all the inferior parts, but only the parts$