Under negative pressure, how does the tympanic membrane (TM) move?

The tympanic membrane, or eardrum, is a vital structure in the auditory system that reacts to changes in pressure in the ear. Under conditions of negative pressure, which occurs when the pressure in the middle ear is lower than the atmospheric pressure present in the ear canal, the tympanic membrane is pulled inward. This movement is a result of the air pressure difference across the membrane.

When negative pressure develops in the middle ear, the external air pressure pushes the tympanic membrane inward toward the middle ear space. This is an essential mechanism for understanding how pressure equalization occurs, as the tympanic membrane's position can influence sound perception and overall ear function. The prosthetic structures in the ear, including the Eustachian tube, help to equalize pressure, and if they fail to do so, it can lead to discomfort or hearing issues.

Therefore, the correct choice reflects the physical response of the tympanic membrane to a state of negative pressure, demonstrating the membrane's function in balance and sound transmission.