Incus

The incus — Latin for 'anvil' — is the middle of the three ear ossicles. It receives vibration from the malleus on one side and passes it to the stapes on the other, through a small knob called the lenticular process. It sits in the upper part of the middle-ear cavity.

Key facts

The incus bridges the malleus and the stapes in the hearing chain.
Its long process ends in the lenticular process, which meets the stapes head.
Its blood supply is relatively delicate, which makes one part vulnerable to damage.
It is suspended by ligaments in the top of the middle-ear space.
Together with the other ossicles it is among the smallest bones in the body.

What can go wrong

The long process of the incus is the part of the hearing chain most often damaged by chronic middle-ear infection, because its blood supply is fragile; this interrupts sound conduction and causes hearing loss. The chain can also be disrupted by head injury or pressure damage from flying or diving with a blocked ear.

Related procedures & tests

Audiometry (hearing test)

Related symptoms

Hearing loss

Frequently asked questions

Which ossicle is which?

From outside in: the malleus (hammer) touches the eardrum, the incus (anvil) sits in the middle, and the stapes (stirrup) presses on the inner ear's oval window. Sound crosses them in that order.

How small is the incus?

Only a few millimetres across — roughly the size of a grain of rice — yet it is a true bone with joints at both ends.

Educational information only. This atlas explains normal anatomy and describes conditions in general terms; it is not medical advice and does not replace assessment by a qualified clinician. If you have symptoms that worry you, seek medical care.