Inferior pharyngeal constrictor
(anatomy) The thickest constrictor muscle that is located inferior to the other pharyngeal constrictor muscles, arises from the sides of the cricoid and thyroid cartilages, and makes up the inferior pharynx
The inferior pharyngeal constrictor is innervated by the vagus nerve via the pharyngeal plexus and the neuronal branches from the recurrent laryngeal nerve.
The inferior pharyngeal constrictor is comprised of the superior muscle, the thyropharyngeus, and the inferior muscle, the cricopharyngeus. The two muscles arise from the sides of the thyroid cartilage and the cricoid cartilage, respectively. These muscles participate in the swallowing of food: the thyropharyngeus contracts while the cricopharygeus relaxes (and vice versa).1 In that way, the thyropharyngeus propels the food whereas the cricopharyngeus allows the passage of food (bolus) from the pharynx to the esophagus.2
1 Kulkarni, N. V. (2006). Clinical anatomy for students: problem solving approach. New Delhi: Jaypee Bros. Medical Publishers.
2 Seikel, J. A., King, D. W., & Drumright, D. G. (2010). Anatomy & physiology for speech, language, and hearing (4th ed.). Clifton Park, NY: Delmar Cengage Learning.