Dry cornea can result from anesthetizing which nerve?

Dry cornea can result from anesthetizing which nerve?

• A. Facial nerve
• B. Infraorbital nerve
• C. Inferior alveolar nerve
• D. Mental nerve

Answer: (A)

Lacrimation is driven by parasympathetic fibers that travel with the facial nerve. The pathway starts with the greater petrosal nerve joining the nerve of the pterygoid canal to reach the pterygopalatine ganglion; postganglionic fibers then hitchhike with branches of the maxillary nerve (via the zygomatic and lacrimal routes) to the lacrimal gland. If this pathway is blocked by anesthesia of the facial nerve, tear production drops, leading to a dry cornea. The other nerves listed are primarily sensory branches supplying the teeth and facial skin; they do not carry the secretomotor parasympathetic fibers to the lacrimal gland, so their anesthesia would not cause dry eye.

Lacrimation is driven by parasympathetic fibers that travel with the facial nerve. The pathway starts with the greater petrosal nerve joining the nerve of the pterygoid canal to reach the pterygopalatine ganglion; postganglionic fibers then hitchhike with branches of the maxillary nerve (via the zygomatic and lacrimal routes) to the lacrimal gland. If this pathway is blocked by anesthesia of the facial nerve, tear production drops, leading to a dry cornea.

The other nerves listed are primarily sensory branches supplying the teeth and facial skin; they do not carry the secretomotor parasympathetic fibers to the lacrimal gland, so their anesthesia would not cause dry eye.