After removal of a large polypus, the patient should always be kept under observation for a day or two in case of symptoms of acute inflammation of the mastoid process arising and necessitating further operation.
CHAPTER III
OPERATIONS UPON THE TYMPANIC MEMBRANE AND
WITHIN THE TYMPANIC CAVITY
SURGICAL ANATOMY OF THE TYMPANUM
The tympanic membrane. The chief points to notice when operating on the tympanic membrane are its inclination and its relation to the inner wall of the tympanic cavity.
The normal membrane is inclined obliquely downwards and forwards so that it forms an obtuse angle of 140 degrees with the roof and an acute angle of 27 degrees with the floor of the external meatus. In infants the inclination is even greater.
Its relation to the tympanic cavity varies in its different parts. It lies nearest to the inner wall in the region of the umbo, being only 2 millimetres distant from the promontory, and is furthest from it in the posterior quadrant.
Running backwards, just below the posterior fold, is the chorda tympani nerve, which may be cut through in the act of paracentesis and in division of the posterior fold.
The tympanic cavity. For the purpose of description the portion of the tympanic cavity above the level of the tympanic membrane is known as the attic or epitympanic cavity; whilst the part below its level is called the cellar or hypotympanic cavity (Fig. 186).
