INTRODUCTION

The larynx is a complex constricting and dilating gateway to the trachea. The three primary functions of the larynx are (1) protection of the airway, (2) respiration, and (3) phonation. Laryngeal closure also allows the patient to build up intrathoracic pressure (the Valsalva maneuver) prior to coughing. It is essential for physicians performing diagnostic or treatment procedures in or through the upper aerodigestive tract to be familiar with the larynx. The purpose of this chapter is twofold: (1) to discuss laryngeal anatomy and function, and (2) to suggest an approach to laryngeal examination.

ANATOMY

Although it sits on top of the trachea, the larynx is suspended from the sternum, clavicles, skull base, mandible, and anterior vertebral column by a group of extrinsic muscles. Its skeleton is a series of pieces of cartilage held together by ligaments, elastic membranes, and the intrinsic laryngeal muscles.

Cartilages

The cricoid cartilage forms the base of the larynx. Although the larynx is a tubular structure, the cricoid is the only complete cartilaginous ring in the laryngeal skeleton. Thus, injury to the larynx in the region of the cricoid ring from trauma, tumor, or iatrogenic causes may quickly lead to laryngeal collapse and airway obstruction. The cricoid has a signet ring shape and is much taller posteriorly (20–30 mm) than anteriorly (5–7 mm).