On the structure of the membrana tympani of the human ear / by Joseph Toynbee.

  • Joseph Toynbee
Date:
1851
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Licence: Public Domain Mark

Credit: On the structure of the membrana tympani of the human ear / by Joseph Toynbee. 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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    [ 359 ] VIII. On the Structure of the Membrana Tympani in the Human Ear. By Joseph Toynbee, F.R.S., Fellow of the Royal College of Surgeons of England, Aural Surgeon to St. Mary's Hospital, and Consulting Surgeon to the St. George's and St. James's General Dispensary. Received June 19,—Read June 20, 1850. In conducting researches into the pathological condition of the organ of hearing, I have been impressed with the necessity of ascertaining, with as much precision as possible, the intimate structure of the various tissues entering into its composition. The results to which investigations undertaken with this latter object in view have led me, in reference to the structure of the membrana tympani, it is the purpose of the present paper to detail. It will be observed that the conclusions at which I have arrived, differ materially in various important particulars from those of previous investigators. Examined from the exterior, inwards the membrana tympani consists of the fol- lowing layers:— 1. The epidermis. 2. The proper fibrous layer, composed of— a. The lamina of radiating fibres. b. The lamina of circular fibres. 3. The mucous membrane (Plate III. fig. 1). 1. The epidermis is a thin layer covering the outer surface of the radiating fibrous lamina; it is continuous with the epidermis of the external meatus, and when sub- jected to the process of maceration it can be removed in the form of a small blind pouch, which presents, as it were, a cast of the meatus and of the external surface of the membrana tympani. When floating in water the pouch assumes the form it had when in contact with other tissues, and its internal extremity is convex, correspond- ing with the external concavity of the membrana tympani (fig. 2). The layer of epidermis forming the outermost coat of the membrana tympani is thin, and in the living subject so transparent that the radiating fibrous layer is distinctly seen through its substance: its outer surface is very smooth and capable of reflecting light: this layer presents no appearance of an orifice. 2. The proper fibrous layer of the membrana tympani can be easily separated into two laminae, which, on account of the direction of their component fibres, may be called the radiating fibrous and the circular fibrous laminae. Previous to entering upon an examination of these structures, it is desirable to cite the opinions which eminent anatomists have entertained on the subject.