Question

All of the following belong to the special visceral efferent column EXCEPT:

• A. Glossopharyngeal nerve
• B. Nucleus ambiguus
• C. Vagus nerve
• D. Trigeminal nerve

Hint:

Three are SVE cranial nerves; one is a brainstem nucleus.

Answer 1

The Correct Option is B

Step 1: Special visceral efferent (SVE), also called branchial efferent, fibres supply the skeletal muscles derived from the pharyngeal (branchial) arches. The cranial nerves carrying SVE fibres are the trigeminal (V), facial (VII), glossopharyngeal (IX), vagus (X) and accessory (XI). Step 2: The question lists three nerves (glossopharyngeal, vagus, trigeminal) that are genuine SVE-carrying cranial nerves. Step 3: Nucleus ambiguus is not a nerve at all; it is a brainstem motor nucleus in the medulla that is the SVE source of fibres for cranial nerves IX, X and XI. The question asks which item is not in the SVE column as a nerve, and the odd one out is the nucleus. Step 4: Hence option b (nucleus ambiguus) is the exception, since the other three are SVE cranial nerves while nucleus ambiguus is a nucleus, making b the correct answer.