Which one of the following nerves is not encountered during submandibular gland resection?
**Core Concept**
The submandibular gland is located in the submandibular triangle, and its surgical resection requires careful dissection to avoid damaging surrounding anatomical structures, including nerves. The nerves in this region are responsible for facial sensation and motor function.
**Why the Correct Answer is Right**
During submandibular gland resection, several nerves are encountered, including the marginal mandibular branch of the facial nerve (C), which innervates the muscles of the lower lip and chin. The lingual nerve (A) is also commonly encountered, as it runs close to the gland and provides sensation to the anterior two-thirds of the tongue. The hypoglossal nerve (D) is another nerve that may be encountered, as it runs anteriorly to the gland and controls tongue movements. However, the spinal accessory nerve (B) is not typically encountered during submandibular gland resection, as it is primarily responsible for innervating the sternocleidomastoid and trapezius muscles and is located more posteriorly in the neck.
**Why Each Wrong Option is Incorrect**
**Option A:** The lingual nerve is a branch of the mandibular division of the trigeminal nerve and is commonly encountered during submandibular gland resection due to its close proximity to the gland.
**Option C:** The marginal mandibular branch of the facial nerve is a branch of the facial nerve and is indeed encountered during submandibular gland resection, as it runs close to the gland and innervates the muscles of the lower lip and chin.
**Option D:** The hypoglossal nerve is a cranial nerve that runs anteriorly to the submandibular gland and is often encountered during resection, as it controls tongue movements and is located in close proximity to the gland.
**Clinical Pearl / High-Yield Fact**
During submandibular gland resection, it is essential to identify and preserve the lingual nerve to avoid postoperative numbness or altered sensation to the anterior two-thirds of the tongue. The marginal mandibular branch of the facial nerve should also be identified and preserved to prevent weakness or paralysis of the muscles of the lower lip and chin.
**Correct Answer:** B. Spinal accessory nerve.