Anatomy of the Middle Ear Tympanic Cavity

Middle Ear Anatomy

• The tympanic membrane makes an angle of 45 degrees with the floor of the external auditory meatus.

Blood Supply

• The tympanic branch of the middle meningeal artery enters the middle ear cavity through the petrotympanic fissure.

Venous Drainage

• The superior petrosal sinus drains the veins of the middle ear.

Pressure Regulation

• The Eustachian tube equalizes pressure on either side of the tympanic membrane.

Nerve Supply

• The tympanic branch of the glossopharyngeal nerve (CN IX) supplies the middle ear.

Tympanic Cavity Boundaries

• The tegmen tympani separates the tympanic cavity from the middle cranial fossa.
• The lateral wall of the tympanic cavity is formed by the squamous part of the temporal bone.

Tympanic Cavity Structures

• The tendon of the tensor tympani muscle emerges from the apex of the pyramid in the tympanic cavity.

Posterior Wall Structures

• The antrum of the mastoid process is located below the aditus to the mastoid antrum in the posterior wall of the tympanic cavity.

Bony Floor Variations

• The bony floor separating the tympanic cavity from the superior bulb of the internal jugular vein may be replaced by a thin plate of bone or a fibrous Bridge.