Report on the progress of human anatomy and physiology in the year 1844-5 / [Sir James Paget].

  • James Paget
Date:
1846
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Licence: Public Domain Mark

Credit: Report on the progress of human anatomy and physiology in the year 1844-5 / [Sir James Paget]. Source: Wellcome Collection.

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    chain of the sympathetic. For when any of these parts of the nervous system is included in the magneto-electric current, there is no contraction of the heart, stomach, or intestines ; whence it follows that neither their nerve-fibres nor their centres are directly stimulated in the experiment.* But orderly movements of alternate contraction and relaxation do, in this experiment, ensue in them ; these, therefore, in accordance with the fifth rule, must be reflex movements, regulated by the nervous centres of the several organs, to which centres the stimuli were conveyed by fibres going to them from the vagus, sympathetic, or spinal cord. Physiology of particular nerves. Third Nerve. Among these expe¬ riments by Volkmann, are somef which show that when the third nerve is stimulated by the magneto-electric current, the voluntary muscles of the eye are thrown into contraction, which ceases on the instant of withdrawing the stimulus, while the contraction of the iris is sometimes prolonged beyond that time. In the voluntary muscles, the contraction indicates that they were stimulated directly through their nerves; in the iris it indicates a stimulus received by it through a centre; and Volkmann suggests that the difference is explicable only by supposing that there are in the trunk of the third nerve fibres which convey centripetal impressions to the ophthalmic ganglion, as to a centre from which the stimulus is conveyed to the nerves of the iris. Fifth Nerve. Two interesting and well-observed cases of paralysis of the fifth nerve on the left side are recorded by Mr. Dixon.}; In one (a woman fifty-three years old) there was (on the paralysed side) loss of motion in the muscles of mastication, and loss of common sensation in the conjunctiva, Schneiderian membrane, tongue, and skin of the face, except near and about the angle of the jaw. There was also complete loss of taste on the edge and forepart of the left half of the tongue, though on all other parts of the tongue the sense was perfect; and on the same side, there were loss of smell, partial loss of hearing, impaired vision, and cessation of the flow of tears while weeping at the other eye. Subsequently, the paralysis involved the third, and perhaps the optic nerve, of the same side. In the other case, the losses of nervous power were similar, but they were complicated by neuralgia of some of the branches of the fifth, and by inflammation (perhaps connected with the paralysis) of the conjunctiva, cornea, and other parts of the left eye. [In regard to the question whether the sense of taste be perceived through the fifth, or the glosso-pharyngeal nerve, these cases, like several others, are less decisive than at first they seem ; for in those parts of the tongue in which the fifth nerve is distributed, it may only supply, as it does in the eye and the nose, a certain condition which is necessary in order that the special sense may be exercised through a special nerve. Even the facial nerve appears to have an office in the tongue essential to the sense of taste; yet it is not itself the nerve of taste]. M. Marehal (de Calvi)§ has related five cases, in which paralysis of the third nerve followed neuralgia of the fifth. One patient had diplopia without apparent deviation of the globe, which ceased on compression of the external frontal nerve. In two of the cases, the neuralgia followed a wound of a branch of the fifth nerve. Facial Nerve. Under the title of the* Anatomy of the Geniculate Ganglion,’ * In experiments by E. H. Weber (Arch. G6n. de Physiologie, Janv. 1846), it is said that the heart ceased to beat on strongly electrifying the pneumogastric nerves, and that its action was weakened and retarded when the stimulus of the nerves was less. + L c. p. 426. I Medico-Chirurgical Transactions, vol. xxviii, p. 373. 5 Bull, de l’Acad^mie Royale de M&iecine, 15 Oct. 1845.