An anatomical study of the recurrent laryngeal nerve: its branching patterns and relationship to the inferior thyroid artery

Abstract

The aim of this study was to provide information about the morphology and topography of the recurrent laryngeal nerve (RLN), its external features and branches, as well as its relationship to the inferior thyroid artery, the inferior horn of the thyroid cartilage and the thyroid gland. The RLNs in 50 adult cadavers (100 sides) were dissected and analyzed. A communicating loop connecting one branch of the RLN to another or a twig originating from the cervical sympathetic trunk was present in 13 of 100 sides. A double left RLN appeared in 2 sides; a right non-recurrent inferior laryngeal nerve appeared in one side. All of the RLNs, including looped ones, bifurcated into laryngeal branches and extralaryngeal branches, with most of the former further dividing into the anterior and posterior branches entering the larynx. The relations of the RLN to the inferior thyroid artery, the inferior horn of the thyroid cartilage and the thyroid gland were inconstant. The information gained from this study will be of value in thyroid surgery.

An applied anatomical study on the recurrent laryngeal nerve and inferior thyroid artery

“…Noteworthily, although the variations of RLN in present study have resemblance to the previous reports [20], the variation types differ from previous one in some aspects. First, the morphology of the looped RLNs in present study was much more complicated than previous report [20], not only in external features, but also in branching patterns.…”

“…Giving more researches on these variations is essential to prevent damage to the nerve. Many authors [3,7,16,[20][21][22][23] noted variations in the branching and position of the RLN, as well as the existence of the non-recurrent inferior laryngeal nerve. According to the present study, variations of the RLN are not only in branching and position, but also in the external morphology of RLN itself.…”

Verlaufsvariet�ten des Nervus laryngeus inferior

“…dem Cornu inferior cartilaginis thyreoideae zur Anwendung kommen [48,65].Kaudal findet sich der NLIR in oder in unmittelbarer Nähe der durch Speise-und Luftröhre gebildeten ösophagotrachealen Rinne.Da er sich der ösophagotrachealen Achse rechtsseitig von lateral annähert und oftmals nach ventral verlagert ist, geht die distale Prä-paration und verfrühte Dissektion der unteren Polgefäße gerade hier mit dem immanenten Risiko der Nervenläsion einher. Die Arteria thyreoidea inferior wird über-oder unterkreuzt,der Nerv kann jedoch auch durch die diversen Ramifikationen verlaufen,eine solche oder die Stammarterie selbst in einer Schlingenbildung umfangen [63]. In einer Übersichtsarbeit werden 28 Variationen beschrieben [52].…”

“…Der Eintrittspunkt des NLIR in die Pars cricopharyngea des M. constrictor pharyngis inferior liegt durchschnittlich 8 mm vom Cornu inferior cartilaginis thyreoideae im dorsokaudalen Quadranten [36]. In seiner Endstrecke kann er multiple (bis zu 9) Ramifikationen oder auch eine plexusartige Verzweigung aufweisen [18,21,63].Gewöhnlich finden sich jedoch 2 Äste, wobei der ventral gelegene motorischer Natur ist,die innere Kehlkopfmuskulatur innerviert und somit in Hinblick auf den Erhalt der Stimmbandfunktion nochmals erhöhter Aufmerksamkeit bedarf [36, 37, Abb. 2a, b Luxation des NLIR aus seiner retrothyreoidalen Lage durch a ein nach retroviszeral vorwachsendes Tuberculum Zuckerkandl oder b eine retrosternale Struma ascending (III).A nonrecurrent nerve on the left is extremely rare,as it can only be found as a combination anomaly of a right-sided lusorian artery with situs inversus viscerum.The divided inferior laryngeal nerve shows recurrent and nonrecurrent ramifications.A nonrecurrent inferior laryngeal nerve can be indirectly ruled out preoperatively by demonstration of a normally developed brachiocephalic trunk via colour-coded duplex ultrasound.…”

A variant nerve that mimics the left recurrent laryngeal nerve: a case study in human anatomy

“…The inferior thyroid artery is sometimes used as an anatomic landmark in search for the RLN (Sun et al, 2001), but this is problematic, because the relationship of the RLNs to the inferior thyroid arteries is so variable, not only from patient to patient but even between the left PrePrints and right sides in a single individual. Reed (1943) reported that the right and left recurrent laryngeal nerve were alike in only 43 of 253 cadavers (17%).…”