Nervous and mental diseases . l reflex hasbeen described by is elicited by percussingover the supra-orbital nerveeither at the point where itemerges or somewhat higherup in its field, and consists ofa fibrillary twitching of theorbicularis palpebrarum. Itshould not be confounded withthe palpebral reflex. It is absent in severe injury or disease of thefacial and of the fifth cranial The pupillary reflex is manifest under several conditions : (1) Ifthe eyes have been closed for a few moments and then suddenly openedin a strong light, or if in a dark room a beam of light is t
Nervous and mental diseases . l reflex hasbeen described by is elicited by percussingover the supra-orbital nerveeither at the point where itemerges or somewhat higherup in its field, and consists ofa fibrillary twitching of theorbicularis palpebrarum. Itshould not be confounded withthe palpebral reflex. It is absent in severe injury or disease of thefacial and of the fifth cranial The pupillary reflex is manifest under several conditions : (1) Ifthe eyes have been closed for a few moments and then suddenly openedin a strong light, or if in a dark room a beam of light is thrown uponthem, the dilated pupils quickly contract. (2) The normal eye showsa decided pupillary contraction if focused on a near object—say, at eightinches—after being directed at a distance of over twenty feet. Thislatter is sometimes called the ciliary reflex. These normal reactions arevariously modified by disease. They may be simply sluggish, they maybe entirely absent, or they mav be dissociated, in locomotor ataxia. Fig. 4.—Method of eliciting the jaw-jerk. 1 Gehirn Pathologie, 2 Brain, 1910. 3 1905, II. Auflage. Neurol. Centralbl., Sept. 1901. 34 NERVOUS AND MENTAL DISEASES. and in paretic dementia, when the posterior portions of the cervical cordare sclerosed, the pupils usually are narrowly contracted. They thenrespond to efforts of visual accommodation only, and are quite insensi-tive to light. This is known as the Argyll-Robertson pupil. Rarelythe opposite condition has been noted in other diseases. The action ofcertain drugs on the pupil, as opium and belladonna, is always to be keptin mind when looking for this reflex, and the eyes must be separatelyobserved, as only one may be affected. The patient must not be allowedto close the eyes vigorously in testing for the pupillary reflex to light, asthis act causes the pupils to dilate, though covered by the lids. In cer-tain conditions, when a portion, usually one-half, of the retina is blind orinsensitive, a
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