Which structure is the tympanic cavity part of?

• A. Ear canal
• B. Tympanic cavity
• C. Middle ear
• D. Round window

Answer: (B)

The main idea is how the ear is organized into external, middle, and inner regions, with the tympanic cavity being the air-filled chamber that forms the middle ear. The tympanic cavity is the central space within the temporal bone that houses the auditory ossicles and is bounded by the tympanic membrane on one side and the bony walls of the middle ear on the others. The ear canal is the external passage leading to that membrane, and the round window is a boundary opening to the inner ear, not the space of the middle ear itself. So the tympanic cavity is the defining space of the middle ear, making it the best fit among the options given, since it directly identifies the cavity itself as the structure in question.