After removal of the parotid gland, patient is having sweating on the cheeks while eating. The nerve involved in this phenomenon
**Core Concept**
The phenomenon described is an example of aberrant regeneration of a nerve, where the fibers of the auriculotemporal nerve (ATN) grow into the nerve stump of the facial nerve (cranial nerve VII) during the healing process after parotid surgery. This results in the misdirected transmission of parasympathetic fibers to the sweat glands.
**Why the Correct Answer is Right**
During normal development, the ATN carries preganglionic parasympathetic fibers from the glossopharyngeal nerve (cranial nerve IX) to the otic ganglion, which then synapses with postganglionic fibers that innervate the parotid gland. After parotidectomy, these fibers can grow into the facial nerve stump, leading to the aberrant innervation of sweat glands on the face. This phenomenon is a result of the close anatomical relationship between the ATN and the facial nerve.
**Why Each Wrong Option is Incorrect**
**Option A:** The glossopharyngeal nerve (cranial nerve IX) is responsible for carrying the preganglionic parasympathetic fibers to the otic ganglion, but it is not directly involved in the phenomenon of aberrant regeneration.
**Option B:** The hypoglossal nerve (cranial nerve XII) is a motor nerve that supplies the tongue, and it is not related to the phenomenon described.
**Option C:** The trigeminal nerve (cranial nerve V) is a sensory nerve that provides general sensation to the face, but it is not involved in the aberrant regeneration phenomenon.
**Option D:** The vagus nerve (cranial nerve X) is a mixed nerve that carries parasympathetic fibers to various organs, but it is not directly involved in the phenomenon of aberrant regeneration after parotid surgery.
**Clinical Pearl / High-Yield Fact**
It is essential for surgeons to be aware of the close anatomical relationship between the ATN and the facial nerve to prevent this phenomenon during parotid surgery. This can be remembered using the mnemonic "ATN + FN = Sweat on the Cheek".
**Correct Answer: A. Auriculotemporal nerve**