After parotidectomy, numbness on the during shaving is due to damage of:
**Core Concept**
The facial nerve, also known as cranial nerve VII, is responsible for controlling the muscles of facial expression, including those involved in movements of the face, such as smiling and frowning. The nerve also provides sensory innervation to the anterior two-thirds of the tongue and the external auditory meatus.
**Why the Correct Answer is Right**
During a parotidectomy, the surgeon is at risk of damaging the facial nerve, which can lead to numbness or weakness of the muscles of facial expression. This is because the facial nerve runs through the parotid gland and is closely associated with the gland's duct and surrounding tissues. Damage to the facial nerve can result in paralysis of the muscles of facial expression, leading to difficulties with movements such as smiling, frowning, and eye closure. The numbness on the face during shaving is likely due to damage to the buccal branch of the facial nerve, which provides sensory innervation to the skin of the face.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not relevant to the scenario described. The trigeminal nerve, also known as cranial nerve V, is responsible for sensory innervation to the face, but it is not the primary nerve at risk during a parotidectomy.
* **Option B:** The glossopharyngeal nerve, also known as cranial nerve IX, is responsible for sensory innervation to the posterior one-third of the tongue and the pharynx, but it is not the primary nerve at risk during a parotidectomy.
* **Option C:** The vagus nerve, also known as cranial nerve X, is responsible for a wide range of functions, including control of the larynx and pharynx, but it is not the primary nerve at risk during a parotidectomy.
**Clinical Pearl / High-Yield Fact**
During a parotidectomy, the surgeon must take great care to identify and preserve the facial nerve, as damage to the nerve can result in significant morbidity, including facial weakness and numbness.
**Correct Answer:** C. Facial nerve