Stapedius muscle

Stapedius Muscle

Diagram of the stapedius muscle in the middle ear

The stapedius muscle is the smallest skeletal muscle in the human body. It is located in the middle ear and plays a crucial role in the auditory system by stabilizing the stapes bone, which is one of the three ossicles in the ear.

Anatomy

The stapedius muscle originates from the posterior wall of the tympanic cavity and inserts into the neck of the stapes bone. It is innervated by the facial nerve, specifically the nerve to stapedius, which is a branch of the facial nerve.

Function

The primary function of the stapedius muscle is to control the amplitude of sound waves entering the inner ear. When the muscle contracts, it pulls the stapes bone away from the oval window of the cochlea, reducing the transmission of sound vibrations. This action is part of the acoustic reflex, which helps protect the inner ear from damage due to loud noises.

Clinical Significance

Dysfunction of the stapedius muscle can lead to a condition known as hyperacusis, where normal sounds are perceived as excessively loud. This can occur due to damage to the facial nerve or other pathologies affecting the middle ear.

Related Structures

The stapedius muscle works in conjunction with the tensor tympani muscle, another small muscle in the middle ear that helps dampen sounds, particularly those produced by chewing.

Related pages

• Middle ear
• Ossicles
• Facial nerve
• Hyperacusis
• Acoustic reflex