The musculus tensor tympani, also known as the tensor tympani muscle, is a small skeletal muscle found in the middle ear. It is one of the two muscles that attach to the auditory ossicles, which are the tiny bones responsible for transmitting sound from the eardrum to the inner ear.
The musculus tensor tympani originates from the cartilaginous part of the Eustachian tube, specifically from the bony canal called the petrous part of the temporal bone. From there, it runs forward and upward to insert into the handle of the malleus bone, which is one of the three auditory ossicles.
The primary function of the musculus tensor tympani is to tense the tympanic membrane, also known as the eardrum. This action reduces the amplitude of incoming sounds, thereby protecting the delicate structures of the inner ear from excessive vibrations. It is an involuntary muscle, innervated by the trigeminal nerve, specifically the mandibular branch.
The musculus tensor tympani also plays a role in various reflex actions. For example, it can contract in response to loud or sudden noises, known as the tympanic reflex or acoustic reflex. This reflex helps regulate the sensitivity of the ear to loud sounds. Additionally, the contraction of this muscle can occur during yawning, swallowing, or chewing, contributing to the prevention of unwanted sounds or noise interference.
