The cricopharyngeus muscle sits at the top of the esophagus. It's function is to relax to allow food and water to swallow and then to tighten up again to prevent gastric reflux of food contents back into the throat. Occasionally the cricopharyngeus muscle remains overly tight and loses its ability to relax with swallowing. This can be diagnosed on a modified barium swallow study.
The treatment for cricopharyngeal hypertrophy is to cut the muscle to prevent it from chronically constricting. This can usually be done endoscopically without making any cuts in the neck. A Botox injection in the cricopharyngeus muscle can be a nice temporary option to determine if division of the cricopharyngeus muscle will improve swallowing permanently.