Background. Variations of recurrent laryngeal nerve (RLN) and Zuckerkandl’s tubercle (ZT), which is posterior extension of lateral lobes, may affect safety of thyroidectomy. Methods. Total and hemithyroidectomy were surgical procedures in 60 and 40 patients, respectively. Surgical anatomy was studied in 87 right and 73 left lobes. Presence of ZT was noted and its incidence was determined. RLNs were identified and fully isolated. Relationship between ZT and RLN was established. Results. ZTs were identified in 66 (66%) patients and in 81 (51%) lobes. ZT was present in 53 (61%) right and in 28 (38%) left lobes. ZTs were bilateral in 15 (25%) of 60 total thyroidectomy cases. Smaller tubercles show the neurovascular crossing point. RLN was posterior (medial) to ZT in 76 (94%) occurrences. RLN was laying on anterior surface of ZT only in 5 (6%) instances. Conclusions. RLN is unusually laying lateral to ZT which is common structure in the thyroid. Lateral RLN may be more vulnerable to injury. Total thyroidectomy requires dissection of ZT adjacent to RLN. Based on unusual relations and variations, RLN should be fully isolated before excision of adjacent structures. 1. Introduction A thyroid surgeon must have intimate knowledge about all anatomic variations of the gland affecting the safety of surgical operations. Emil Zuckerkandl (1849–1910), an Austrian anatomist has described many anatomical structures in the body [1, 2]. Zuckerkandl’s tubercle (ZT) is defined as posterior extension of the lateral lobes composing of thyroid tissue only [3]. It should be included in the Nomina Anatomica as the “processus posterior glandulae thyroideae” described by Zuckerkandl [4]. It is classified into four groups according to size [5, 6]. The surgical importance of ZT can be summarized as (1) dissection and excision of ZT for total thyroidectomy and (2) close relationship between ZT and recurrent laryngeal nerve (RLN). The completeness of thyroidectomy requires removal of enlarged ZT which is posterolateral extension of thyroid lobes adjacent to RLN. Close relation of two structures urges careful, fine, and very close dissection around the nerve. Due to posterior location of an enlarged ZT, thyroid surgeon must be focused on its relations with inferior laryngeal nerve for safe identification of the nerve and resection of the tubercle. The presence of ZT and close association of RLN to an enlarged tubercle has been documented in many patients [7–10]. We aim to study the presence of ZT, its relations with RLN, and variations of this relationship during surgical dissection of
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