Objectives: To describe the course of the superior laryngeal nerve (SLN) and its branches, in particular, with regard to supraglottic motor and sensory functions.
Methods: In 30 normal human hemilarynges, the SLN with its internal (intSLN) and external branch (extSLN) were dissected under microsurgical conditions and marked with acrylic dye. All anatomic structures of the larynges (muscles, cartilages, and ligaments) were dissected in detail.
Results: The intSLN subdivides into three branches. The superior branch (I) runs to the lingual (extralaryngeal) part of the epiglottis and sends small fibers through the epiglottic foramina to the laryngeal surface. The middle branch (II) runs through the aryepiglottic fold into the ventricular fold, and the inferior branch (III) to the piriform sinus and to the postcricoid region, forming various anastomoses (e.g., ansa galeni) with the recurrent laryngeal nerve (RLN). The extSLN runs to the cricothyroid muscle (CT) and sends a branch through the CT along the lower rim of the thyroid cartilage into the larynx and up to the ventricular fold. This ventricular branch is a potential candidate for the innervation of the ventricular muscle (VM).
Conclusions: Our results may contribute to a better understanding of supraglottic actions that provide primary functions of the larynx (such as swallowing, coughing, and breathing). An enhanced knowledge of neurolaryngology also provides a basis for interpreting disorders or paralyzes following surgical treatments (e.g., thyroid surgery, partial laryngectomy) and helps to lower the risks.