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Incudostapedial Joint

articulatio incudostapedialis

The incudostapedial joint is the tiny synovial joint between the lenticular process of the incus and the head of the stapes, the last link in the ossicular chain of the middle ear. It passes sound vibrations from the incus to the stapes, whose footplate then moves the fluid of the inner ear through the oval window.

Anatomical Data

Structure

Bones	Lenticular process of the long limb of the incus Head of the stapes
Ligaments	Articular capsule

Biomechanics

Function & Actions

Movements	Very small movements that transmit vibration from the incus to the stapes Slight gliding that allows for differences in incus and stapes motion

Clinical Relevance

Clinical Notes

The long process of the incus near this joint has a poor blood supply, so it is the part of the ossicular chain most often eroded by chronic otitis media and cholesteatoma. The incudostapedial joint is also the most common site of traumatic ossicular discontinuity, which causes a large conductive hearing loss. Repair uses bone cement, a reshaped incus or a prosthesis to reconnect the incus and stapes.

Pathology

Common Injuries & Conditions

Incudostapedial Joint Separation

Traumatic disruption of the incus-stapes link, the most common traumatic ossicular injury, causing a marked conductive hearing loss that is repaired by ossiculoplasty.

Erosion of the Long Process of the Incus

Loss of bone at the incus end of the joint from chronic otitis media or cholesteatoma, breaking the ossicular chain and producing conductive hearing loss.

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