Laryngeal Nerves: Surgical Importance in Relation to the Thyroid Arteries, Thyroid Gland and Larynx

Abstract

The variation in the course and direction of the recurrent laryngeal nerve on the right and on the left side may be explained on an embryologic basis. As the heart and the great vessel of the chest, the aorta, descend from their point of origin behind the face, they carry this nerve with them. This is also applicable to the descent of the right subclavian artery. Both of the recurrent nerves have their point of origin in close proximity to the vessels just mentioned. They are carried downward by the descent of these structures during embryonic life. This can be demonstrated in the presence of an anomalous position of these vessels. Such a condition is accompanied by an anomalous location of the respective nerves.1 From this brief description of the embryology, the variability that the recurrent nerve may assume can be appreciated. Gross deviations are rare; slight modifications are not uncommon.Pemberton and Beaver2 reported a case in which the right recurrent nerve was found at thyroidectomy to arise from the cervical portion of the vagus on a level with the superior pole of the thyroid gland. Milianitch3 reported a similar case. The nerve is usually described as supplying all of the intrinsic muscles of the larynx except the cricothyroid. Its importance in phonation and respiration is academic knowledge.

Surgical Anatomy of the Extralaryngeal Aspect of the Superior Laryngeal Nerve

“…The ibSLN has been described as always accompanied by the superior laryngeal artery, and this nerve mostly remains cranial to that artery. 18,19,22 Our findings showed that most ibSLNs (89%) were in a parallel and medial position to the superior laryngeal artery, whereas they were located inferiorly and medially to the superior laryngeal artery in 11% of dissections.…”

Relationship of the recurrent laryngeal nerve to the inferior thyroid artery: A comparison of findings from two systematic reviews

“…For MA using data from SR1, numbers were modified for Page et al () by excluding 78 “divided” RLNs (as described above) and for Lekacos et al () for the right side (total 109 RLNs), where the numbers for anterior and “between” had been transposed in SR1 (vs. the original report and SR2). For the Ziegelman () study, 42% anterior on the left side in SR1 was verified (i.e., 8/19), vs. 32% in SR2, but no analyses for SR2 were done for this review. For the Reed () study, used only in SR1, data were verified; 27 divided RLNs had been included in the “between” category in SR1 (vs. excluded in data tabulated for both sides combined, as described above).…”

Variable relationship of the recurrent laryngeal nerve to the inferior thyroid artery: A meta‐analysis and surgical implications

“…The characteristics of the studies included in the meta‐analysis are summarized in Table , which shows the prevalence of each type of RLN to ITA relationship. A total of 79 studies ( n = 14,269 nerves) were included, among which 18 were intraoperative, 60 were cadaveric, and 1 included both intraoperative and cadaveric groups. Among the intraoperative studies, 5 were prospective and 14 were retrospective.…”