Small cavity between the eardrum and the inner ear.

• A. Outer ear
• B. Inner ear
• C. Ear canal
• D. Middle ear

Answer: (D)

The space behind the eardrum that is small and air-filled is the middle ear. It sits between the tympanic membrane and the inner ear, and it contains the three tiny auditory bones that transmit vibrations from the eardrum to the inner ear. It also connects to the throat via the Eustachian tube to equalize pressure. The outer ear comprises the pinna and ear canal, while the inner ear contains the cochlea and balance organs; the ear canal is part of the outer ear. So the described cavity is the middle ear.