Functional anatomy of the recurrent and superior laryngeal nerve

The purpose of this study was to present the current topographic and anatomical knowledge in neurolaryngology, with special regard to laryngeal paralyses as a major complication in thyroid surgery.

Microscopic anatomical preparation of 22 human hemilarynges was accomplished.

Due to their neuroanatomical courses, the following extralaryngeal nerves may be at risk in thyroid surgery: the external branch of the superior laryngeal nerve, the paralaryngeal part of the vagal nerve, the Ansa Galeni, the trunk of the recurrent laryngeal nerve (RLN) and the delicate branches of the RLN to the posterior cricoarytaenoid muscle. The anterior and posterior branches of the RLN (antRLN and postRLN) are less endangered by thyroid surgery because they are covered by the thyroid cartilage and posterior cricoarytaenoid muscle (PCA), respectively. In contrast, the antRLN is vulnerable if a ventilation tube is dislocated, with cuff-induced pressure to the glottic level.

The increased knowledge in neurolaryngology provides the basis for a selective neuromonitoring to lower the risk of laryngeal paralyses after thyroid surgery.