Cricopharyngeal Muscle Dysfunction refers to when the cricopharyngeal muscle (CPM) in your throat malfunctions or is impaired, which can cause you to have difficulty swallowing. The top valve of your esophagus (food pipe) is called the upper esophageal sphincter (UES), or pharyngoesophageal segment (PES). The CPM separates the esophagus and throat. Unlike most muscles, the CPM remains flexed and tightly closed unless nerves signal it to relax. This protects the throat and windpipe from food or liquid coming back up and inadvertently entering the lungs. For food, liquid, and saliva to enter the esophagus, the CPM needs to relax while these contents pass through the esophagus.