Abstract

The resting and deglutitive pressures in the pharynx, pharyngo-oesophageal sphincter, and upper oesophagus were obtained from 32 healthy intact dogs. The dogs were divided into groups and submitted to either bilateral denervation or muscle ablation. Manometric studies were repeated two weeks and four weeks after operation. Bilateral division of the pharyngo-oesophageal nerve reduced the resting sphincteric pressure and the amplitude of the pressures of sphincteric relaxation and contraction after deglutition. Bilateral division of the recurrent laryngeal nerves or bilateral division of the cervical sympathetic trunks did not alter sphincteric resting or deglutition pressures. Muscle ablation involving the cricopharyngeus muscle reduced resting sphincteric pressure, shortened the zone of elevated pressure, and decreased the amplitude of the pressure responses to deglutition. These findings confirm that the cricopharyngeus muscle is the upper oesophageal sphincter and that it receives its motor innervation from the pharyngo-oesophageal nerve, a branch of the pharyngeal plexus that comes primarily from the vagus nerve.