malleus

Meaning: The malleus (hammer) is the first of three tiny middle-ear bones, the ossicles, followed by the incus (anvil) and stapes (stirrup). It is attached to the tympanic membrane, so eardrum vibrations pass from the malleus to the incus to the stapes, which pushes on the oval window of the cochlea. The ossicles act as a lever, and the eardrum is much larger than the oval window, so pressure is amplified as sound enters the fluid-filled inner ear.

On the MCAT: Expect questions that order the path of sound: pinna, auditory canal, tympanic membrane, malleus, incus, stapes, oval window, cochlear fluid, basilar membrane and hair cells, auditory nerve. A passage may describe stiff or damaged ossicles and ask for the effect: less vibration reaches the cochlea, so sound conduction is impaired.

Common confusion: The malleus does not turn sound into neural signals; it only transmits mechanical vibration. Transduction happens when hair cells in the cochlea bend and the auditory nerve fires. Also keep the order straight: the hammer touches the eardrum, and the stirrup touches the oval window.