The normal tympanic membrane is thin and semi-transparent. When viewed through an otoscope it has a pearly grey appearance and often some structures within the middle ear, such as the long process of the incus and the opening of the eustachian tube, can be seen if it is sufficiently transparent. Where the outer margin of the drum is attached to the external canal it is thickened and called the annulus fibrosa. The upper one-fifth of the drum is slack and called the pars flaccida and the lower four-fifths called the pars tensa. The handle of the malleus, which extends downwards and backwards, is a reliable landmark. The short process of the malleus protrudes forwards into the external canal. The umbo is the central attachment of the tympanic membrane to the malleus. From the umbo a cone of light extends downwards and forwards. The blood supply of the tympanic membrane comes from the ear canal superiorly. Prominent blood vessels on the rim superiorly are within normal limits.
Wax, or cerumen, is a normal secretion in the cerumenous glands in the outer part of the meatus, and can obscure or partially obscure the drum. When it is first produced it is colourless and semi-liquid in consistency, but with time it changes from pale yellow to golden yellow, to light brown and finally black. As the wax darkens it also hardens and the darker the colour the denser the consistency.
Acute otitis media with effusion. There is distortion of the drum, prominent blood vessels in the upper half with dullness of the lower half. There is also bulging of the upper half of the drum and the outline of the malleus is obscured
Further example of acute middle ear infection with effusion. The handle of the malleus is obscured, and fluid levels are obvious behind the eardrum.
Acute otitis media with no recognisable land marks. There is considerable bulging of the ear drum with purulent fluid behind a tense tympanic membrane which sometimes heralds perforation. In some cases incision of the drum is required.
Appearance of serous (secretory) otitis media. The eardrum has lost its lustre and an effusion is visible through the eardrum with a fluid meniscus defining the upper margin.
Fluid behind the ear drum in asymptomatic child. Effusion is visible with a fluid level in the lower half of the eardrum. The handle of the malleus is also difficult to visualise.
Resolution of middle ear effusion. The handle of the malleus is still foreshortened and horizontal. Signs in the upper half of the eardrum suggest that fluid is still present in the middle ear.
A further example of serous otitis media. There is indrawing of a dull ear drum and the handle of the malleus is characteristically horizontal. Eustachian tube obstruction had led to failure of replacement of air which is normally absorbed from the middle ear resulting in vacuum formation and effusion of fluid.
Tympanosclerosis. In some cases of otitis media healing may not be completed and the inflammatory process leads to the formation of scar tissue. This can take the form of calcified plaques on the tympanic membrane.
Central perforation of the ear drum. Perforations are usually single but may be multiple. Spontaneous rupture of the drum can occur in association with acute infection when the tense drum perforates and releases pus. The ear drum illustrated has a long standing perforation accompanied by tympanosclerosis of the drum.
Grommet -Tympanostomy tube. Grommets can be inserted in the tympanic membrane if medical treatment and myringotomy are unsuccessful and the child has persistent middle ear effusion. The illustration is a silicone tube retained in an opening in the drum by inner and outer flanges.