This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Physiology
If a person has normal musculature but has difficulty swallowing, which nerves should be tested for function? 
Select and explain. 
A. Hypoglossal and phrenic, B. Hypoglossal and splanchnic, C. Glossopharyngeal and vagus, D. Splanchnic and vagus
D: Splanchnic and vagus
Answer: D: Splanchnic and vagus 
Explanation: The upper 2/3 of the esophagus contains striated muscle. It is derived from the pharyngeal arches and innervated by the vagus nerve (CN X). The lower 1/3 contains smooth muscleft from splanchnic mesoderm and is innervated by the splanchnic plexus.