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VIII. On the Structure of the Memhrana 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 memhrana 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 memhrana 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. 
