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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    respondence, though in opposite conditions, the one contracted, the other re- laxed. And now as to the motions of the eye, we cannot be surprised if the mus- cle exterior to the eyelids, and the muscle lying deep in the socket should be re- lated in the condition of relaxation and contraction, and that the relation should be established through the connection of their respective nerves at their roots— this is the matter to be enquired into. Let us now attend to the relation of the lesser portion of the orbicular mus- cle—that paler set of fibres which lies on the eyelids. When we recollect that the margins of the eyelids in closing, touch only at their outer edge, and that when closed, a gutter is left between them and the cornea, the winking of the eye, far from clearing the surface of the cornea, would suffuse it, by leaving the tear upon it, were it not that in the act of winking the eyeball is turned up. It is by this revolving of the ball, that the cornea is moist- ened and wiped clear. How is this revolving motion of the eyeball accomplished ? No action of the eyelids could produce this effect. It can only be done by the action of superior rectus or inferior oblique. It is not performed by the superior rectus, which I determined, by cutting that muscle in a monkey, when the upward rolling of the cornea continued accompanying the effort of the eyelids to close. The two oblique muscles being opponents, the relaxation of the upper one will give power to the lower one, so that we have, as before, to seek for a relation between the paler fibres of the orbicularis and the superior oblique. The supe- rior oblique stands in the same relation to the internal and paler circle of the orbicularis that the abducens or rectus externus does to the stronger exterior circle of the same muscle. Thus brought to acknowledge the relation between the muscle seated on the eyelid and external, to a muscle seated deep in the orbit, and seeing no direct connection between them, we must turn once more to notice the relations which establish the connection at the roots or origins of their respective nerves. By such study of the muscular apparatus of the eye, and their actions for the protection of the organ, we are following out the principle, that the structure and action of a part will direct us to the peculiarity of its nerves. That the eye stands distinguished from the other organs of sense by the multiplicity of its guards, is owing to its extreme delicacy of structure, and its necessary exposure. In my second paper, I had occasion to notice that the facial nerve, or portio dura of the seventh, coming circuitously through the foramen stylo-mastoideum to supply the face, is the nerve also of the orbicularis palpebrarum, or, in other words, of the exterior muscles of the eyelids. It was also noticed, that the fa- cialis at its origin is in direct relation with the sixth or abducens nerve. Now, this sixth nerve takes a direct course forwards into the bottom of the eye-socket, E