The organs of vision : their structure and functions / by G.J. Witkowski ; tr. by Henry Power.

  • Gustave-Joseph Witkowski
Date:
[1878?]
Catalogue details

Licence: Public Domain Mark

Credit: The organs of vision : their structure and functions / by G.J. Witkowski ; tr. by Henry Power. 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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    Some anatomists incorrectly regard the zonule of Zinn (153) as a process of the hyaloid. It is true that these two membranes are adherent at the periphery of the zone (152), but they soon separate to enclose the festooned walls of the canal of Petit. Diseases of the vitreous humour are rare; its fluidification, or synchysis, however, has been observed. Fibrinous flocculi may float in it, and give rise to subjective sensations named muscce voUtantes, but these more frequently proceed from disease of the retina or choroid. Digitalis taken in a certain dose produces similar troubles : hence its common name of herlue. II. APPENDAGES OF THE EYE. There are certain additional organs which enter into the forma- tion of the visual apparatus and serve to protect and move the globe. These appendages are the eyebrows, the lids, and lacrymal apparatus; the muscles, and suspensory apparatus; and lastly, the cavity of the orbit in which they are contained. 1. The Eyebrows.—These are' formed of two more or less projecting hairy arches, the function of which is to protect the visual apparatus from too intense light, and to prevent the en- trance into the eye of irritating sweat descending from the brow. Phrenologists are much in error in considering prominence of the supraciliary arch (14) a sign of intelligence. The bony pro- jections on which the eyebrows are implanted have not, in point of fact, any relation with the development of the anterior lobes of’ the brain, since their size is entirely dependent on that of the cavities situated in the anterior part of the frontal bone, named the frontal sinuses. The eyebrows owe their extreme mobility to the supraciliaris (22) frontalis and orbicularis palpebrarum (4, 5) muscles, the numerous fibres of which are inserted into the deep surface of the skin in this region. Wounds of the eyebrows are sometimes followed by amaurosis, or loss of vision, though no explanation can be offered of this result. The sensory nerve of the skin of the frontal region and of the upper lid, is the supra-orbital, which emerges from the orbit by the fissure or foramen of the same name. Excision of this nerve has been recommended and practised in cases of neu- ralgia which have proved rebellious to other means. 2. Eyelids.—The eyelids are situated in front of the orbit, and are destined to protect the eyes in the same way as the eyebrows. They serve to favour sleep, and to facilitate the flow of tears over the ocular surface. Each eye possesses two eyelids, an upper and a lower. They are separated hj theioal]yel>ral fissure, the extremi