Introduction
The stapes bone is the smallest and lightest bone in the entire body. It is present in the middle ear along with other ossicles (malleus and incus) of the ear. It helps in transmitting sound waves in the hearing process. It is also called stirrup bone. It is situated against the oval window (a connective tissue membrane present at the end of the middle ear and the beginning of the inner ear) of the inner ear.
What Is a Stapes Bone?
The stapes are one of the auditory ossicles in the middle ear. It is the smallest and lightest bone in the human body.
Parts of the ear are the external ear, middle ear, and inner ear.
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The outer ear consists of a pinna, ear canal, and eardrum (tympanic membrane).
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The middle ear consists of the eardrum and ossicles.
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The inner ear consists of the cochlea, semicircular canals, and nerve cells.
The stapes bone is stirrup-shaped with parts like a head, neck, anterior and posterior limb, and base. The base rests on the oval window of the inner ear. The head joins the incus bone through the incudostapedial joint. This joint is a synovial joint which is of ball and socket type. The neck part of the stapes is attached to the stapedius muscle. Its primary function is to transmit sound to the inner ear. Three ossicles are interconnected. The malleus is hammer-shaped. It strikes the incus, which is anvil-shaped. Vibrations travel through stapes. Stapes are compared to tuning forks and measure about 2 to 3 millimeters (mm), greater at the head base span.
If any damage to the stapes occurs due to injury to the head or other reasons, the hearing process is affected, and the individual may lose hearing because these bones are connected in a chain.
What Is the Function of the Stapes Bone?
Stapes bone hits the oval window and generates waves in the inner ear's fluid. This wave in the fluid initiates the process in the inner ear. In the inner ear, sound waves are converted into electrical signals the brain interprets. The vibration of the stapes bone is essential for hearing. Sound waves cannot travel to the inner ear if the stapes bone cannot vibrate.
What Are the Conditions Associated With Stapes Bone?
Conditions associated with stapes bone are otosclerosis and cholesteatoma.
Otosclerosis:
Otosclerosis is derived from the word oto, which means ‘of the ear,’ and sclerosis, ' abnormal hardening of body tissue'. Otosclerosis is a condition in which abnormal bone remodeling of auditory bones occurs due to which stapes bone is fixed in a place. In this condition, stapes cannot generate waves in the inner ear fluid, resulting in hearing loss. The cause of otosclerosis is unknown, may be hereditary, and generally affects middle-aged women.
Symptoms of otosclerosis are
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The hearing may be lost.
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Dizziness causes a balancing problem.
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Tinnitus (ringing in the ears) may develop.
Hearing loss occurs in one ear and then slowly affects another ear. This condition may be treated by hearing aids for loss of hearing and by performing stapedectomy (removal of stapes bone).
Cholesteatoma:
It is a congenital condition in which there is an abnormal growth of skin occurring in the eardrum. It occurs due to repeated infections of the inner ear that involve fluid. It also causes deterioration of auditory bones, including stapes.
Symptoms of cholesteatoma:
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Drainage of the ear.
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Pressure in the ear.
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Loss of hearing.
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Ringing in the ear (tinnitus).
Complications of cholesteatoma occur if it is not treated on time. Some of the complications are the following:
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Loss of hearing results in total deafness.
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Brain abscess.
The treatment depends on the extent of hearing loss and the growth of the skin.
Otitis Media:
It is an inflammation of the middle ear. As all ossicles are located in the middle ear, they get affected due to chronic infections. Bacterial and viral infections cause otitis media.
The following are the symptoms of otitis media:
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Pain in the ear.
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Appetite loss.
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Lack of sleep.
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Irritable nature.
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Difficulty in hearing.
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Drainage from the ear.
What Is the Treatment for These Conditions?
Appropriate treatment at the right time helps prevent hearing loss due to various conditions. This also helps stop damage and deterioration of ossicles and their chain in the middle ear. There are many treatment options present for the needs.
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Antibiotics are to be given in case of infection present.
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Allergic conditions that contribute to infection must be treated.
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Surgical procedures are to be performed whenever necessary.
The placement of synthetic ventilation tubes may be done surgically to drain and restore the normal pressure in the middle ear. This is a simple procedure that does not have complications. Recovery time is also fast after this procedure.
When damage to the stapes bone is present due to other conditions, total or partial ossicular replacement (TORP or PORP) procedure is done to restore hearing. The success rate is good in this procedure, with rare complications associated.
Before the surgery, the procedure's benefits and demerits will be explained by the healthcare provider. Postoperative pain and vertigo (balancing problem) may develop, which get improve gradually. Tympanoplasty can be done to correct the problem in the bones.
Side effects of stapedectomy surgery are
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Dizziness and Nausea: These are common after the surgery.
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Taste Change: There may be a temporary change in the taste as a nerve related to taste passes under the eardrum.
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Loss of Hearing: High-frequency hearing loss may be present, but improvement in other frequencies makes up.
Side effects of stapedotomy are
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Infection.
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Chemical irritation.
Conclusion
The ear is an essential organ of the body. It performs the function of hearing. Small ossicles in the middle ear are essential in conducting sound waves to the inner ear. Stapes bones play a vital role in the hearing process. Hence it is important to know about stapes bone, its function, associated conditions, and treatments. Knowing about it helps an individual to seek help from a healthcare provider early. Early diagnosis is the key to effective treatment. This, in turn, allows one to lead a good quality life.
