Extramucosal myotomy of the pharyngoesophageal sphincter muscle, ie, the cricopharyngeal muscle, is a widely used therapy for dysphagia due to neurologic diseases. The cricopharyngeal muscle is dissected free via a lateral cervical incision. To cut the muscle fibers it is necessary to expose and to stretch them. A device is developed to make this possible. A light source is brought within a cuffed tube. The tube is inserted in the esophagus with the cuff in the cricopharyngeal sphincter. Inflating the cuff with air causes stretching of the muscle fibers, whereas the light source inside makes all muscle fibers visible. They can be cut carefully, leaving the mucosa intact.