A Cadaveric Study of the Course and Anatomical Relations of the Recurrent Laryngeal Nerve with the Inferior Thyroid Artery and Thyroid Gland

Abstract

Background: The recurrent laryngeal nerve (RLN) is a major motor nerve of the larynx and is closely related to structures routinely encountered during thyroid and other cervical operations. Variations in its course, branching pattern and relation to the inferior thyroid artery (ITA), thyroid gland, ligament of Berry and Zuckerkandl’s tubercle may increase the difficulty of identification and preservation.

Methods: A gross anatomical dissection and observational study was performed on 25 embalmed human cadavers, providing 50 RLNs, 25 on each side. The origin and looping pattern, relation to the tracheo-oesophageal groove (TOG), angle with the TOG, extralaryngeal branching, relation to the ITA, thyroid gland, Zuckerkandl’s tubercle, ligament of Berry and cricothyroid joint were recorded.

 Results: All 50 RLNs arose from the vagus nerve. The right RLN looped around the first part of the right subclavian artery and the left RLN looped beneath the aortic arch lateral to the ligamentum arteriosum. The nerve was within the TOG in 60% of right and 80% of left sides. Extralaryngeal branches were present in 64% of nerves overall. Posterior relation to the ITA was observed in 66%, anterior relation in 24%, and passage between ITA branches in 10%. All nerves were free from the thyroid gland, superficial to the ligament of Berry and medial to the Zuckerkandl’s tubercle; all passed posterior to the cricothyroid joint before entering the larynx.

Conclusion: The RLN demonstrates important side-to-side and individual anatomical variation. Identification of the nerve should not depend on a single landmark. The TOG, ITA, Zuckerkandl’s tubercle, ligament of Berry and cricothyroid joint should be considered together during surgical dissection.