Transoral Surgical Anatomy and Clinical Considerations of Lateral Oropharyngeal Wall and Base of Tongue

Abstract

Objectives: (1) Describe key anatomic structures in lateral oropharyngeal wall and tongue base transorally. (2) Determine surgical landmarks to increase intraoperative safety in transoral robotic surgery. Methods: Transoral dissections were performed endoscopically in 5 vascular silicone-injected fresh human cadavers. Anatomic structures were also confirmed with lateral neck dissections. Results: Tonsillar bed is largely made by superior pharyngeal constrictor muscle and overlying pharyngobasilar fascia. Palatoglossus and palatopharyngeus muscles limit this tonsillar bed anteriorly and posteriorly, forming tonsillar pillars. Stylopharyngeus and styloglossus muscles and stylohyoid ligament run between superior and middle pharyngeal constrictor muscles contributing to inferior tonsillar fossa. These structures are located just medial to facial, lingual, and internal maxillary arteries in parapharyngeal space. Internal carotid artery lies posterolateral to the branches of external carotid artery. Lingual artery injury might occur during base of tongue or inferior tonsil resections. At its origin, the lingual artery is situated deep to middle pharyngeal constructor muscle between stylohyoid ligament and greater cornu of hyoid bone posteriorly. At the tonsil-tongue base junction, it courses lateral and deep to styloglossus muscle. Keeping the resection over styloglossus muscle and stylohyoid ligament will prevent lingual artery injury. The glossopharyngeal nerve is positioned between stylohyoid ligament and styloglosus muscle. Its branches travel posteroinferiorly in inferior tonsillar fossa toward the base of tongue. Lingual nerve is vulnerable to injury as it emerges anterior to medial pterygoid muscle. Conclusions: A thorough understanding of transoral anatomy is critical for surgeons to perform transoral robotic surgery safely and efficiently.