Inferior pharyngeal constrictor

The pharyngeal muscles are a group of muscles that form the pharynx, which is posterior to the oral cavity, determining the shape of its lumen, and affecting its sound properties as the primary resonating cavity. The pharyngeal muscles (involuntary skeletal) push food into the esophagus. There are two muscular layers of the pharynx: the outer circular layer of pharyngeal constrictor muscles and the inner longitudinal layer. The outer circular layer includes: Superior constrictor muscle Middle constrictor muscle Inferior constrictor muscle During swallowing, these muscles constrict to propel a bolus downwards (an involuntary process). The inner longitudinal layer includes: Stylopharyngeus mus (Wikipedia)