Which of the following nerve loops around submandibular duct?
**Core Concept**
The question is testing the student's knowledge of the anatomical relationship between the submandibular duct and the surrounding nerves. The submandibular duct, also known as the Wharton's duct, carries saliva from the submandibular gland to the oral cavity.
**Why the Correct Answer is Right**
The lingual nerve, a branch of the mandibular division of the trigeminal nerve (CN V3), loops around the submandibular duct as it exits the submandibular gland. This relationship is clinically important because the lingual nerve is at risk of injury during surgical procedures involving the submandibular gland or duct. The looping of the lingual nerve around the submandibular duct also makes it a common site for nerve compression or injury.
**Why Each Wrong Option is Incorrect**
* **Option A:** The facial nerve (CN VII) is responsible for facial expressions, taste to the anterior two-thirds of the tongue, and other functions, but it does not loop around the submandibular duct.
* **Option B:** The hypoglossal nerve (CN XII) innervates the tongue muscles and does not have a relationship with the submandibular duct.
* **Option D:** The glossopharyngeal nerve (CN IX) is involved in swallowing, taste, and other functions, but it does not loop around the submandibular duct.
**Clinical Pearl / High-Yield Fact**
The lingual nerve is at risk of injury during surgical procedures involving the submandibular gland or duct, which can result in numbness or altered sensation to the anterior two-thirds of the tongue.
**Correct Answer: C. Lingual nerve.**