<prompt> Which of the following muscle produces abduction of vocal cord? RepeatTransverse arytenoidPosterior cricoaryteniodLateral cricoarytenoidOblique arytenoid  <response>: Ans: B Posterior cricoarytenoid Ref: Grays Anatomy, 39th edition. 2008.Page 642Explanation:Posterior cricoarytenoid :The only muscle produce abduction of vocal cord open the rimu glottides and it becomes triangular in shapeSo called the Safety muscle of larynxOrigin: Posterior surface of lamina of cricoid cartilageInsertion: Muscular process of arytenoid cartilageNerve supply: Recurrent laryngeal nerve branch of vagusBlood supply: Laryngeal branches of superior inferior thyroid arteriesTo remember :Safety muscle of tongue is genioglossus 