The tensor tympani muscle is innervated by the nerve to medial pterygoid (mandibular nerve, CN V3). Its primary action when it contracts is to:

• A Tense the tympanic membrane by rotating the malleus laterally and posteriorly
• B Tilt the malleus handle inferiorly to increase membrane tension
• C Retract the tympanic membrane to reduce sound transmission
• D Tense the tympanic membrane by pulling the handle of malleus medially and anteriorly ✓

Explanation

The tensor tympani runs in a bony canal above the Eustachian tube; its tendon hooks around the processus cochleariformis and inserts onto the medial surface of the malleus handle. Contraction draws the malleus handle anteromedially, increasing tympanic membrane tension and reducing its mobility. This provides a protective effect against intense sounds and is also activated during chewing (why chewing can temporarily muffle hearing). The stapedius (innervated by CN VII) pulls the stapes posteriorly and is the primary muscle of the acoustic reflex.

Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.