Incus

The primary function of the incus is to facilitate the efficient transfer of sound vibrations. When sound waves enter the ear canal, they strike the tympanic membrane (eardrum), causing it to vibrate. These vibrations are then transmitted to the malleus, which is attached to the eardrum. The malleus moves the incus, which, in turn, pushes the stapes against the oval window of the cochlea in the inner ear. This process amplifies the sound vibrations, allowing them to be converted into nerve impulses by the delicate hair cells within the cochlea, ultimately leading to the perception of sound. This amplification is critical, as sound waves must be increased in intensity to overcome the barrier created by the fluid-filled inner ear.

The incus is located in the middle ear, which is situated between the outer ear and the inner ear. Specifically, the incus is positioned posterior to the malleus and anterior to the stapes, forming an essential part of the ossicular chain. It hangs in the air-filled cavity of the tympanic cavity, secured by ligaments that allow it to pivot slightly, facilitating its role in transmitting sound vibrations. The entire middle ear is found within the temporal bone of the skull, nestled just behind the eardrum and connected to the throat via the Eustachian tube.

• The incus is shaped somewhat like an anvil, which is how it got its name.
• In humans, the incus measures about 0.8 centimeters in length.
• The incus can also be found in other mammals, playing a similar role in the process of hearing.
• In certain cases, congenital defects can lead to the absence or malformation of the incus, resulting in hearing loss.
• The incus is one of the few bones in the body not covered by muscle, resting instead in a delicate network of ligaments.