Six months after recovering from a left lower motor neuron facial palsy, a patient reports tearing of the left eye every time he eats. The mechanism is BEST explained by which process?
- A Regeneration of chorda tympani secretomotor fibres into the greater petrosal nerve pathways supplying the lacrimal gland ✓
- B Loss of parasympathetic supply to the lacrimal gland with compensatory reflex tearing
- C Damage to the deep petrosal nerve causing denervation hypersensitivity of the lacrimal gland
- D Regeneration of glossopharyngeal secretomotor fibres into the facial nerve trunk
Correct answer: A. Regeneration of chorda tympani secretomotor fibres into the greater petrosal nerve pathways supplying the lacrimal gland
Explanation
Gustatory lacrimation, or crocodile tears, follows aberrant regeneration after proximal seventh nerve injury. Preganglionic parasympathetic fibres originally destined for the submandibular and sublingual glands via the chorda tympani regenerate along the greater petrosal nerve route, synapse in the pterygopalatine ganglion, and now activate the lacrimal gland instead of salivary glands whenever salivation is stimulated. Glossopharyngeal fibres supply the parotid via the otic ganglion and play no role here.
Reference: Snell's Clinical Neuroanatomy, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.