Tensor tympani

The tensor tympani is one of the two muscles in the middle ear cavity that module the movement of the auditory ossicles.

Anatomical details

1. Origin

• Cartilaginous part of the pharyngotympanic (auditory) tube.

• Greater wing of the sphenoid bone.

• The muscle lies within a narrow bony canal situated superior to the bony part of the auditory (Eustachian) tube. Within this canal, its fibres run parallel to the bony portion of the tube and are separated from it by a bony septum called the canalis musculotubarius. Some fibres also arise from the walls of this osseous canal itself.

2. Insertion

The tensor tympani muscle passes posteriorly through its canal and ends in a slender tendon that enters the tympanic cavity, hooks sharply around the end of the septum, and inserts into the handle (manubrium) of the malleus near its root..

Innervation

Mandibular division of the trigeminal nerve (CN V3​) via the nerve to tensor tympani, a small branch of the medial pterygoid nerve, which itself arises from CN V3​.

Blood supply

Superior tympanic artery, a branch of the middle meningeal artery, which in turn is a branch of the maxillary artery.

Actions

• Primary action: Pulls the handle of the malleus medially, thereby tensing the tympanic membrane.

• Contracts reflexively in response to loud sounds and during self‑vocalization or mastication, restricting excessive movement of the tympanic membrane and ossicles. This dampens vibrations—particularly of loud, low‑frequency sounds (e.g., chewing and other self‑generated noises)—stabilizes auditory perception, and helps protect the cochlea from mechanical overstimulation.

Clinical correlation

• Paralysis or injury of the tensor tympani or its nerve (rare) may slightly reduce damping of self‑generated sounds, producing a sensation of a “full ear” or mild sound sensitivity (mild hyperacusis).

• By contrast, dysfunction of the stapedius muscle due to a CN VII lesion is far more clinically important and typically causes hyperacusis, in which ordinary sounds are perceived as abnormally loud.