The chorda tympani nerve runs through the middle ear in a specific fascial fold. If it is injured during tympanomastoid surgery, the immediate neurological deficit NOT expected is:

• A Loss of lacrimation from the ipsilateral lacrimal gland ✓
• B Loss of taste from the anterior two-thirds of the ipsilateral tongue
• C Decreased salivation from the submandibular and sublingual glands
• D Dry mouth worse on the affected side

Explanation

Chorda tympani carries taste from the anterior two-thirds of the tongue (special visceral afferent) and preganglionic parasympathetic fibres to the submandibular ganglion, which supplies the submandibular and sublingual glands. Lacrimation is mediated by the greater petrosal nerve (CN VII fibres proximal to chorda tympani), not the chorda tympani itself. Therefore, injury to the chorda tympani in the middle ear does NOT affect lacrimation.

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.