Interrelationships between the innervations from the laryngeal nerves and the pharyngeal plexus to the inferior pharyngeal constrictor.

PURPOSE: The inferior constrictor is innervated by the pharyngeal plexus and the external and recurrent laryngeal nerves. The communication between these nerves may influence the innervations. However, the relations of their anastomoses with the innervations have been unclear. This gross anatomical study re-examined the configuration of the inferior constrictor and investigated the variations of the anastomoses and the innervations of the constrictor to clarify their interrelationships.
METHODS: The inferior constrictor and the branches of the superior and recurrent laryngeal nerves and the pharyngeal plexus were examined under a binocular microscope in 30 Japanese cadavers.
RESULTS: The inferior constrictor consisted of the oblique fibers from the thyroid and cricoid cartilages and the horizontal ones from the cricoid. The oblique fibers were innervated by the pharyngeal plexus from the dorsal and ventral surfaces. The external laryngeal nerve gave twigs to the oblique fibers and the cricothyroid from the lateral surface. The recurrent laryngeal nerve supplied the horizontal fibers from the ventral surface. The internal laryngeal nerve sometimes and the main trunk of the superior laryngeal nerve rarely supplied the upper oblique fibers. The communicating branches between the laryngeal nerves and the pharyngeal plexus sometimes gave twigs to the constrictor from the dorsal surface.
CONCLUSIONS: The innervations to the inferior constrictor from the laryngeal nerves and the pharyngeal plexus are classified into some types based on their branching patterns and anastomoses, suggesting that the dysfunctions of the laryngopharyngeal region vary according to the positional relationships between the affected part and the innervations types.