Stapedius Muscle Essay

Cassidy Carrion

Monica Vogler

10/19/2015

Middle Ear Ossicles There are numerous structures of the hearing mechanism that affect the transmission of sound to the cochlea. While the majority of these structures promote amplification of sound, the muscles of the middle ear actually serve to protect hearing from damage caused by loud sounds. The tensor tympani and stapedius muscle work together to activate the acoustic reflex when needed. The tensor tympani and the stapedius muscle serve to “increase resonant frequency of the middle ear to protect the inner ear from high sound pressure levels”(Pau, Punke, Zehlicke, Dressler, & Sievert, 2005). The stapedius muscle is a short muscle located in the pyramid section of the temporal bone. It is attached to the stapes, which inserts in the oval window of the cochlea. The stapedius muscle pulls on the stapes to prevent it from moving too much. The tensor tympani is a muscle that attaches to the manubrium, or handle, of the malleus. The manubrium terminates at the umbo. The tensor tympani pulls laterally on the malleus to tense, or stiffen the tympanic membrane. This stiffening of the tympanic membrane attenuates, or lessens the force of oscillation when activated by the

Common sounds in the environment such as doorbells, whistling tea kettles, and car horns are all sounds that can excite the acoustic reflex. If the acoustic reflex is stimulated on one side, ipsilaterally, it will also cause the contralateral, or opposite side to be activated. The acoustic reflex it stronger and faster when evoked ipsilaterally as compared to contralaterally. However, even the ipsilateral reflex is too slow to protect against sudden impulse or transient noise (Pau, Punke, Zehlicke, Dressler, & Sievert, 2005). The muscles cannot remain contracted long-term, ruling out protection against continuous loud