Table of ContentsView AllTable of ContentsAnatomyFunctionAssociated ConditionsTreatment

Table of ContentsView All

View All

Table of Contents

Anatomy

Function

Associated Conditions

Treatment

Theincus, also called the “anvil,” is the middle of three small bones (called ossicles) in the middleear. The incus transmits vibrations from the malleus to the stapes. The vibrations then move to theinner ear.

Conditions involving the incus affect hearing and often affect the other two ossicle bones.

The incus sits between the other two bones, known asossicles, of the middle ear. Themalleus(“hammer”) is the outermost bone and thestapes(“stirrup”) is the innermost. Theossiclesare part of the auditory system, and together, they comprise an area about the size of an orange seed.

Incus is Latin for “anvil,” which is why it is sometimes referred to as such. It gets its name from the shape of the bone.

Anatomic Variations

Defects of the ossicles can include hypoplasia (under-development) and displacement.

A birth defect calledcongenital aural atresiahappens when the external auditory canal doesn’t fully develop. This condition may be associated with other congenital anomalies.

The ossicles also work to protect the ear from loud sounds. When the muscles of the middle ear contract in response to loud noise, the eardrum’s ability to vibrate is reduced. This reduces the movement of the incus and the other ossicles, limiting the damage that might otherwise occur from the impact of the noise.

Due to its role in transmitting sound, conditions of the incus often affect hearing. In fact, conditions of the incus are rarely isolated and most often involve all three bones.

Otosclerosis

Symptoms include:

Diagnosis usually involves audiography andtympanometry, which help to determine hearing sensitivity. Acomputed tomography(CT scan) may also be done in order to view the ossicle bones and confirm the diagnosis.

Dislocation

Dislocation of any of the ossicle bones can occur as a result of trauma or other conditions. Ossicular chain dislocation, as it’s known, can happen from:

Symptoms of dislocation might include:

A CT scan is usually used to diagnose dislocation of the ossicle bones. To determine the extent of hearing loss, tympanometry and audiography may also be used.

Cholesteatoma

Congenital aural atresia

Congenital aural atresia is one of the more challenging conditions to treat.

Non-surgical treatment includes bone conductionhearing aids, which transmit sound vibrations through bones in the head. These can be magnetic or surgically implanted.When surgery is done, it attempts to fully restore hearing and usually happens when a child is 6 or 7 years old.

Studies have shown these types of hearing aids do offer good hearing outcomes and recent advances have improved the technology. These devices should be placed as early as possible to be most effective.

Otosclerosis treatment options can be supportive (treating symptoms) or curative. Hearing aids and sodium flouride supplements are examples of supportive treatments.

Curative treatments involve surgical restoration. In a stapedectomy, the damaged bone (usually the stapes) is removed and replaced with a synthetic implant.

Ossicular chain dislocation

Ossicular chain dislocation most often requires a kind of surgery calledossiculoplasty. During the surgery, the ossicular chain is reconstructed to improve hearing.

The success rate of ossicular chain dislocation repair depends on whether the stapes is intact or not with a better rate of good hearing recovery if the stapes is intact.

Summary

The incus is one of three small bones in the middle ear that works to transmit sound to the inner ear. Related conditions usually involve all three bones and affect hearing. Treatment will depend on the condition and may involve surgery and/or supportive treatments such as hearing aids or supplements.

7 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.National Institute on Deafness and Other Communication Disorders.Otosclerosis.Stanford Medicine.Ossicular chain dislocation.Keck Medicine of USC.Ossicular chain dislocation.Medline Plus.Cholesteatoma.Lee MY, Cho YS, Han GC, Oh JH.Current treatments for congenital aural atresia.J Audiol Otol. 2020;24(4):161-166. doi:10.7874/jao.2020.00325American Hearing Research Foundation.Otosclerosis.Penn Medicine.Cholesteatoma.

7 Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.National Institute on Deafness and Other Communication Disorders.Otosclerosis.Stanford Medicine.Ossicular chain dislocation.Keck Medicine of USC.Ossicular chain dislocation.Medline Plus.Cholesteatoma.Lee MY, Cho YS, Han GC, Oh JH.Current treatments for congenital aural atresia.J Audiol Otol. 2020;24(4):161-166. doi:10.7874/jao.2020.00325American Hearing Research Foundation.Otosclerosis.Penn Medicine.Cholesteatoma.

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

National Institute on Deafness and Other Communication Disorders.Otosclerosis.Stanford Medicine.Ossicular chain dislocation.Keck Medicine of USC.Ossicular chain dislocation.Medline Plus.Cholesteatoma.Lee MY, Cho YS, Han GC, Oh JH.Current treatments for congenital aural atresia.J Audiol Otol. 2020;24(4):161-166. doi:10.7874/jao.2020.00325American Hearing Research Foundation.Otosclerosis.Penn Medicine.Cholesteatoma.

National Institute on Deafness and Other Communication Disorders.Otosclerosis.

Stanford Medicine.Ossicular chain dislocation.

Keck Medicine of USC.Ossicular chain dislocation.

Medline Plus.Cholesteatoma.

Lee MY, Cho YS, Han GC, Oh JH.Current treatments for congenital aural atresia.J Audiol Otol. 2020;24(4):161-166. doi:10.7874/jao.2020.00325

American Hearing Research Foundation.Otosclerosis.

Penn Medicine.Cholesteatoma.

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