The malleus, also called a “hammer” or “hammer,” is the largest of the three small bones in the middle ear. The malleus works with other bones to transmit vibrations from the eardrum to the inner ear. Conditions that affect the malleus often affect hearing.
The malleus (“hammer”), incus (“anvil”), and stapes (“stirrup”) are the three bones of the inner ear, also known as the ossicles.
The malleus is the largest and outermost bone and is part of the auditory system. The three bones together make up an area no larger than the seeds of an orange.
The ossicles are suspended in the middle ear by ligaments. The malleus is shaped like a hammer, hence its Latin name. It is located in the middle ear between the incus and the eardrum. The parts of the malleus include:
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A joint holds the head of the malleus and the incus together.
Deformities of the ossicles include hypoplasia (underdevelopment) or displacement.
Congenital atresia is a birth defect that occurs when the external auditory canal does not fully develop. It can be related to other congenital anomalies and is one of the most difficult to correct.
The sensory function of the auditory bone is hearing. The bones work together to transmit sound waves from the outer ear to the inner ear. They do this by bringing vibratory pressure from the tympanic membrane to the malleus, then the incus, then the stapes, and finally the cochlea.
Bones also play a protective role.
When exposed to loud noises, the muscles of the middle ear contract, reducing the ability of the eardrum to vibrate. This in turn reduces movement of the malleus and the other two ossicles and limits the impact of noise.
Since the malleus plays a vital role in transmitting sound, the condition of the malleus often affects hearing.
Otosclerosis is a type of hearing loss caused by abnormal bone growth in one or more of the ossicles. When this happens, the bones stick together, restricting their ability to move, preventing normal hearing. Hearing loss is the main symptom of otosclerosis and usually occurs gradually. Tinnitus and dizziness may also occur.
If your healthcare provider suspects you have otosclerosis, they may order an audiogram and tympanogram to determine your hearing sensitivity. A computed tomography scan (CT scan) to look at the ossicles can confirm the diagnosis.
ossicular chain dislocation
Bone dislocation can occur after trauma. This condition, known as a dislocation of the ossicular chain, can occur from blows to the head, loud explosions, injuries from instruments used in the ear canal, and injuries from air or water pressure. Symptoms of dislocation include hearing loss, facial paralysis, ringing in the ears, and vertigo.
Ossicular dislocation is usually diagnosed by CT scan. Tympanometry and audiograms can help determine the extent of hearing loss.
Cholesteatoma is a noncancerous abnormal skin growth in the middle ear. If it gets too big, it can damage the ossicles. Symptoms include hearing loss, ear pressure or pain, dizziness, ear drainage, and facial paralysis.
The diagnosis of cholesteatoma involves examination of the ear with an otoscope. Your healthcare provider may also order a CT scan to get a clearer picture.
Treatment of disorders affecting the malleus often (but not always) involves surgery. Treatment is provided by an otolaryngologist, a health care provider who specializes in ear, nose, and throat disorders.
Supportive and Therapeutic Treatment
Treatment for otosclerosis can be supportive (treating symptoms) or curative:
- Supportive care includes hearing aids and vitamin and mineral supplements.
- Curative treatment includes surgery. A stapedectomy involves removing the damaged bone (usually the stapes) and replacing it with a synthetic implant.
Surgery may be required in different situations, including:
- Correcting congenital auditory atresia: This is one of the more challenging treatments for disorders affecting the malleus. The goal of surgery is to restore hearing without the need for hearing aids. Surgery usually occurs when the child is 6 or 7 years old.
- Osteoplasty: Repair of a dislocation of the ossicular chain most often involves this procedure. This surgery involves rebuilding the ossicular chain with the goal of improving hearing. The procedure may be contraindicated if the dislocation is in the person’s only hearing ear.
- Surgical removal: Cholesteatoma does not go away on its own, but is treated by surgical removal. Usually, antibiotics and ear drops are prescribed to control infection and reduce swelling before surgery.
bone conduction device
A bone conduction device is a hearing aid that transmits sound vibrations through the bones of the head. They are a non-surgical treatment option for atresia. They can be implanted surgically or used with magnets.
Recent technological advancements have improved these devices, and studies have shown that they can provide good hearing outcomes. For maximum success, they need to be placed early.