Volume 1

A treatise on diseases of the eye, nose, throat, and ear : for students and practitioner ... / edited by William Campbell Posey and Jonathan Wright.

Date:
1903
Catalogue details

Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: A treatise on diseases of the eye, nose, throat, and ear : for students and practitioner ... / edited by William Campbell Posey and Jonathan Wright. Source: Wellcome Collection.

Provider: This material has been provided by The University of Leeds Library. The original may be consulted at The University of Leeds Library.

    35/764 (page 29)
    The pupil is rarely clear black, the anterior surface of the lens re- flecting some light; indeed, this reflex is often so marked in elderly subjects that the grayish film due to sclerosis of the lens is often mis- taken for cataract by the inexperienced observer. If oblique illumi- nation be employed, however, the true nature of the opacity m the lens becomes manifest. Fig. 8. Ganglion trunci vagi- Sup, cervical ganglion- Vagus and sympatUeticX nerves J- Inf. cervical ganglion^ Annulus of Vieussens- Stellate ganglion- Cardiac nerves ICilio-spinal' region Illustrating the paths of Innervation of the Iris. Constrictors from t*^^ ^ gemina by the third nerve, ciliary ganglion and nerves to the circular ^^^l^^^/^^^^^^'^. ^'^^^ from the bulb and cord by anterior roots of the iirst three thoracic nerves, rami communicantes, cervical sympathetic and ganglia, Gassenan ganglion, ophthalmic branch of the fifth nerve, ciliary ganglion and nerves radiating to muscles of ins. (Waller.) The iris is the diaphragm of the eye, and by its action in intercepting marginal rays it prevents an excessive amount ot light from entering the eye. In order that this may be accomplished with great rapidity and the size of the pupil instantly changed, the ins is provided with a delicate mechanism wonderfully adapted to the function which it has to perform. This consists of two antagonistic factors: one, a constrict- ing mechanism, to contract the pupil; the other, a dilating one, to dilate