The chorda tympani nerve, a branch of CN VII, runs across the tympanic membrane. Which precise course does it take through the middle ear?

• A Runs posterior to the malleus handle and anterior to the long process of incus, crossing the superior part of the tympanic membrane ✓
• B Runs anterior to the malleus and posterior to the handle of malleus, below the incus
• C Passes through the floor of the tympanic cavity to enter the infratemporal fossa directly
• D Runs medial to the tensor tympani muscle tendon across the promontory

Explanation

The chorda tympani arises from the facial nerve in the facial canal, enters the tympanic cavity through the posterior wall (iter chordae posterius), arches across the upper part of the tympanic membrane between the mucous membrane and fibrous layer, passing lateral (superficial) to the long process of incus and medial to the upper part (neck) of the malleus. It exits anteriorly through the iter chordae anterius into the infratemporal fossa where it joins the lingual nerve. This course makes it vulnerable during myringotomy or ear surgery, causing taste disturbance in the anterior two-thirds of the ipsilateral tongue.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.