Synonyms
Latin: Musculus stapedius
Definition
The stapes muscle is a middle ear muscle. It protects the ear from high sound levels and thus influences the hearing process. It is particularly important to protect the ear from the volume of your own voice. It is innervated by the facial nerve and can therefore fail if this nerve is damaged and can no longer perform its protective function. The stapedius muscle is the smallest striated muscle in the human body.
History
Base: neck area of the stapes Origin: pyramidal protrusion (Eminentia pyramidalis) Innervation: stapedius nerve of the facial nerve
Function
The stapes muscle is involved in the hearing process. As a rule, it cannot be tensed arbitrarily; its contraction is triggered reflexively when the sound level is too high. The stirrup muscle tightens the ligament anulare, a band that runs around the footplate of the stirrup.
During contraction, the vibrations of the stapes are attenuated and thus transmitted in a reduced form to the oval window. From the oval window, vibrations are transmitted to the perilymph, a fluid of the inner ear. The muscle protects the ear from excessive sound levels by reducing the sound transmission.
Common diseases
If the facial nerve is damaged before the stapedius nerve, which supplies the stapes muscle, is removed, the stapedius reflex fails and the person affected is much more sensitive to noise. In addition to the sensitivity to noise, reduced tear secretion as well as hemiplegia on the affected side occurs, since the facial nerve is also responsible for the innervation of the lacrimal gland and the mimic muscles. There are many causes for such nerve damage.
Besides fractures of the petrous bone, viruses, bacteria, autoimmune diseases of the nervous system or tumors can also lead to lesions of the facial nerve. The therapy depends on the cause of the disease.
