The Pharyngoesophageal Sphincter

Abstract

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 lower cricopharyngeus muscle and those of the upper esophagus, and claimed that the fibers of the cricopharyngeus muscle may be scarce or absent, while the circular fibers of the upper esophagus are usually well developed. However, the upper esophageal sphincter is still referred to in the literature as the cricopharyngeal sphincter. In 1963, we completed an anatomico-roentgen study on the lower esophageal sphincter which we designated the lower esophageal vestibular complex (8). We documented the presence of a structural sphincter corresponding to the vestibular segment. In reviewing some of our films of the opacified pharynx and upper esophagus at rest, we noted the presence of a persistently contracted segment of the upper esophagus 1–2 cm long, located below the level of the lower pole of the cricoid cartilage (Fig. 2). The appearance of this segment so closely resembled the contracted lower sphincter that we surmised the presence of a close structural similarity. Also, because of the location below the lower pole of the cricoid cartilage, it occurred to us that the sphincter might not be the cricopharyngeus muscle. We thus initiated an anatomico-roentgen study of this area similar to the one carried out at the lower end of the esophagus.2 One hundred specimens of this region were studied: 70 of adults ranging in age from ten to eighty-eight years and 30 of infants ranging from a three and one-half month embryo to a one-year-old child. Of the adults, 31 had come to accidental death, and the infants were mostly premature. Of the 70 adult specimens, 67 were dissected and 3 used exclusively for histologic studies. All the infant specimens were used chiefly for histologic sections. In 65 of the adult specimens roentgen studies were also undertaken, and in 12 cast impressions were obtained.