This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Head and neck, Subject name: Anatomy
Which of the following muscle is supplied by 9th cranial nerve? 
Select and explain. 
A. Palatopharyngeus, B. Salpingopharyngeus, C. Stylopharyngeus, D. Superior constrictor of Pharynx
C: Stylopharyngeus
Answer: C: Stylopharyngeus 
Explanation: Stylopharyngeus is the only muscle in the pharynx innervated by the glossopharyngeal nerve (CN IX), others are innervated by the vagus.There are two muscular layers of the pharynxThe outer circular layer includes:Inferior constrictor muscleMiddle constrictor muscleSuperior constrictor muscleThe inner longitudinal layer includes:Stylopharyngeus muscleSalpingopharyngeus musclePalatopharyngeus muscle