This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anatomy of Larynx, Subject name: ENT
Only laryngeal muscle that is innervated bidirectionally is 
Select and explain. 
A. Vocalis, B. Posterior cricoarytenoid, C. Lateral cricoarytenoid, D. Interarytenoid
D: Interarytenoid
Answer: D: Interarytenoid 
Explanation: - Interarytenoid muscle is an unpaired muscle in the centre between the 2 arytenoid cailages and is innervated bidirectionally.