A guide to the study of ear diseases / by P. M'Bride.

  • Peter McBride
Date:
1884
Catalogue details

Licence: Public Domain Mark

Credit: A guide to the study of ear diseases / by P. M'Bride. Source: Wellcome Collection.

    18/236 page 4
    This author therefore suggested the propriety of inserting a thermometer into the ear in doubtful cases. He also found that the temperature is considerably reduced by the internal administration of chloral and opium. The tympanic membrane (syn. drumhead, membrana tympani) is a delicate membrane, more or less ellip- tical in shape, placed obliquely across the extremity of the external auditory canal, and separating it from the cavity of the tympanum. The obliquity is from above and behind downwards and forwards, from which it follows that when the membrane is examined through the meatus, its posterior and superior parts are nearer the examining eye than the anterior and inferior. The manubrium, or handle of the malleus, is attached to the membrane, but its position wiU be better understood when we come to discuss the appearance of the drumhead in the living subject. Histologically, the latter consists of three parts, viz.— (1) A dermoid layer, composed of very delicate skm, continuous with that lining the meatus. (2) A layer of modified connective tissue, spoken of as the sub- stantia propria, consisting of external radiating and internal circular fibres, some of which pass external to the handle of the malleus, while others are attached to it. This middle layer of the membrane is fixed to a ring of bone, which is defective above. This defect is filled up in the recent state by a portion of the di-umhead, which contains no substantia propria, con- sisting of skin and mucous membrane only (Shrapnell's membrane or membrana flaccida). (3) The inner layer is composed of mucous membrane, continuous with that lining the tympanum. Posteriorly it is reflected round the chorda tympani nerve, and forms what has been called by Von Troltsch the posterior
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