THE INNERVATION OF THE HUMAN UPPER ESOPHAGEAL SPHINCTER

The neuroanatomy and physiology of the human upper esophageal sphincte r (UES) has long been controversial. As a result, there has been littl e progress in diagnosing and treating dysphagias involving this area. In this study, three specimens of the UES obtained from human autopsie s were examined by Sihler's stain. This stain clears soft tissue while counterstaining the nerves, thereby allowing nerve supply to each mus cle of the UES to be demonstrated, It was found that the nerve supply to each component of the UES is substantially different. The inferior pharyngeal constrictor (IPC) is supplied by a dense linear plexus whic h is about 1.0-1.5 cm wide and 10 cm long and located about 1.5 cm lat eral to the attachment of the IPC on the thyroid lamina. The cricophar yngeal (CP) muscle receives its innervation from below via the recurre nt laryngeal nerve (RLN) and from above via the pharyngeal plexus. Neu ral connections between the RLN and the pharyngeal plexus were observe d. Finally, the upper esophagus (UE) is innervated by the RLN. The inn ervation pattern of each component of the UES suggests functional diff erences between these muscles, These observations help clarify the inn ervation of the UES. Accurate knowledge of the neuroanatomy of the UES is necessary for advances in diagnosis and treatment of pharyngeal dy sphagia.