If a patient develops a dry eye after local anesthesia, which nerve is most likely anesthetized?

If a patient develops a dry eye after local anesthesia, which nerve is most likely anesthetized?

• A. Facial nerve
• B. Infraorbital nerve
• C. Lingual nerve
• D. Mental nerve

Answer: (A)

Tear production is driven by parasympathetic signals that originate from the facial nerve. These signals travel with the greater petrosal nerve to the pterygopalatine ganglion, then postganglionic fibers reach the lacrimal gland to stimulate tear secretion. If local anesthesia blocks these parasympathetic pathways, tear production drops and a dry eye results. The other nerves listed are sensory branches of the trigeminal nerve and do not carry secretomotor fibers to the lacrimal gland. Blocking them would numb areas but not reduce tear production, so they’re less likely to produce a dry eye.

Tear production is driven by parasympathetic signals that originate from the facial nerve. These signals travel with the greater petrosal nerve to the pterygopalatine ganglion, then postganglionic fibers reach the lacrimal gland to stimulate tear secretion. If local anesthesia blocks these parasympathetic pathways, tear production drops and a dry eye results.

The other nerves listed are sensory branches of the trigeminal nerve and do not carry secretomotor fibers to the lacrimal gland. Blocking them would numb areas but not reduce tear production, so they’re less likely to produce a dry eye.