Question:medium
During resection of submandibular gland, there is accidental injury to a structure running superior to the posterior belly of digastric muscle. Which of the following structure is likely to be injured?
During resection of submandibular gland, there is accidental injury to a structure running superior to the posterior belly of digastric muscle. Which of the following structure is likely to be injured?
Show Hint
In submandibular gland surgery, always remember the marginal mandibular nerve is at risk.
Updated On: May 14, 2026
- Lingual nerve
- Marginal mandibular nerve
- Trigeminal nerve
- Hypoglossal nerve
Show Solution
The Correct Option is B
Solution and Explanation
Step 1: Understanding the Question:
This is a surgical anatomy question. We must identify a structure based on its topographical relationship to the submandibular gland and the posterior belly of the digastric muscle.
Step 2: Detailed Explanation:
Surgical Risk in Submandibular Surgery: During excision of the submandibular gland, three major nerves are at risk: the Marginal Mandibular Nerve, the Lingual Nerve, and the Hypoglossal Nerve.
Anatomical Relations:
Marginal Mandibular Nerve (MMN): This is a branch of the Facial Nerve (CN VII). It courses deep to the platysma but superficial to the facial vessels and the submandibular gland capsule. Importantly, it loops just below the mandible, running superior to the posterior belly of the digastric.
Hypoglossal Nerve (CN XII): Runs deep to the posterior belly of the digastric muscle and the submandibular gland.
Lingual Nerve: Runs superior to the deep part of the gland, looping around the submandibular duct.
Analyzing the Injury Scenario: The question specifies an injury "superior to the posterior belly of the digastric". Among the nerves at risk, the MMN is the most superficial and superiorly located structure in this region.
Clinical Outcome: Injury to the MMN results in paralysis of the muscles that depress the corner of the mouth (like depressor anguli oris), leading to an asymmetrical smile.
Step 3: Final Answer:
The structure running superior to the posterior belly of the digastric, and thus at highest risk during superficial dissection of the submandibular gland, is the marginal mandibular nerve.
This is a surgical anatomy question. We must identify a structure based on its topographical relationship to the submandibular gland and the posterior belly of the digastric muscle.
Step 2: Detailed Explanation:
Surgical Risk in Submandibular Surgery: During excision of the submandibular gland, three major nerves are at risk: the Marginal Mandibular Nerve, the Lingual Nerve, and the Hypoglossal Nerve.
Anatomical Relations:
Marginal Mandibular Nerve (MMN): This is a branch of the Facial Nerve (CN VII). It courses deep to the platysma but superficial to the facial vessels and the submandibular gland capsule. Importantly, it loops just below the mandible, running superior to the posterior belly of the digastric.
Hypoglossal Nerve (CN XII): Runs deep to the posterior belly of the digastric muscle and the submandibular gland.
Lingual Nerve: Runs superior to the deep part of the gland, looping around the submandibular duct.
Analyzing the Injury Scenario: The question specifies an injury "superior to the posterior belly of the digastric". Among the nerves at risk, the MMN is the most superficial and superiorly located structure in this region.
Clinical Outcome: Injury to the MMN results in paralysis of the muscles that depress the corner of the mouth (like depressor anguli oris), leading to an asymmetrical smile.
Step 3: Final Answer:
The structure running superior to the posterior belly of the digastric, and thus at highest risk during superficial dissection of the submandibular gland, is the marginal mandibular nerve.
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