Three papers on the nerves of the encephalon, as distinguished from those arising from the spinal marrow / by Sir Charles Bell.

  • Bell, Charles, Sir, 1774-1842.
Date:
1838
Catalogue details

Licence: Public Domain Mark

Credit: Three papers on the nerves of the encephalon, as distinguished from those arising from the spinal marrow / by Sir Charles Bell. 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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    the eye, and to none others; so that it directs the axis of the eye in vision, both controlling the muscles, and having the further property of conveying to the mind the impression of the condition of the muscles. I entertain this idea because it is a double nerve. Its origin.—Our best authors describe this nerve as arising from the crus cerebri, and so it does, above all the intricacies of the nervous system. It does not enter into the mixture of originating filaments in the pons or nodus. It does not communicate with the decussation in the medulla oblongata. It is in direct communication with the brain. But its precise origin deserves more particular inquiry. As I have elsewhere shewn, that the crus cerebri consists of two columns, one of motion, the other of sensation, and that the corpus nigrum divides these columns. If a section be made of the crus, just anterior to the origin of the third nerve, we shall find that we cut through the corpus nigrum. And now if we take the cu- rette, and gently divide the two columns, and so separate them in the direction towards the root of this nerve, we shall divide or split it, shewing that part of it arises from the anterior column, and part of it from the posterior column. If we carefully dissect and lay out the third nerve, we have a very interesting view, as illustrative of its function, and of the nervous system in general. The roots, as they arise, and for some way in their course (see the Plate, Figs. 1 and 2), are in round distinct cords, running parallel to each other. They then join to- gether, and form a dense body, in which the filaments are separated, rejoin, and are matted together, after which their progress is as a common nerve. Their dis- tinct origin from the divisions of the crus—the two distinct fasciculi of parallel fibres—the course of these for some way without exchange of filaments, and then afterwards running into intimate union—are circumstances of much inte- rest, as shewing the distinction of the crus cerebri, the distinct nature of the roots of the third nerve, and that it is a double nerve, dedicated to the finer motions of the eye, peculiar in its structure, and yet in conformity with the system which I have followed. * A question is naturally suggested here, Is the third nerve a sensitive nerve, as well as a motor; and if so, how comes it that there is no regular ganglion on the root which it receives from the sensitive column ? This would incline me to believe, that the ganglionic root is an organization on the spinal nerves and fifth pair, suited to that sensibility which the body uni- versally and the surface especially enjoys, which gives pain, and becomes a guard upon the frame. * The objection which will be naturally suggested, is, that the abducens nerve arises behind the pons. We shall afterwards shew why it does so. And, let it not be forgotten, that the relations of this nerve are the cause of frequent disturbance to the condition of the eye, a consequence, certainly, of its greater complexity.