Valsalva in 1717 was the first to name the inferior portion of the inferior constrictor muscle of the hypopharynx the cricopharyngeus muscle (1). Home in 1823, according to Lerche (2), was the first to regard the lower fibers of the cricopharyngeus as the constrictor of the upper end of the esophagus. Killian (3) in 1908 described the cricopharyngeus muscle as consisting of two portions, the upper pars ob-liqua and a lower pars fundiformis, which he believed constituted the constrictor of the upper esophagus. He referred to this part as the“lip” which closes the esophageal orifice or“mouth,” the latter being an area immediately below the lip (Fig. 1). Later investigators questioned this contention—notably Abel (4) and Elze (5). They believed that the circular fibers of the upper esophagus acted as a sphincter. This is also the belief of a number of more recent authors—notably Holmgren and Brombart (6). Perrott (7) stated that some investigators have confused the two sets of circular fibers, those of the l...