Relationship between the Zuckerkandl's tubercle and entrance point of the inferior laryngeal nerve.

The Zuckerkandl's tubercle (ZT) is a lateral or posterior projection from the lateral thyroid lobe. It has been used as an anatomical landmark for location of the inferior laryngeal nerve (ILN). Because most nerve injuries occurred just below that point where the ILN passed under the inferior constrictor muscle, we aimed to investigate the relationship between the ZT and entrance point (EP) of the ILN. Forty-five specimens taken from 26 male and 19 female cadavers were dissected. We found Grade 2 and Grade 3 ZTs in 58 sides (64% of 90 sides). The ZT was situated at the middle third of lateral lobe of the thyroid gland in 48 sides (82.7% of 58 sides). This group had three subgroups: (I) the ZTs indicated EPs of the ILN or the anterior laryngeal branch, (II) the ZTs covered the EPs of the ILN or the laryngeal branches or only the anterior laryngeal branch, and (III) the ZTs were below or above the EPs of the laryngeal branches. In conclusion, the ZTs pointed the EPs of the ILN or the laryngeal branches in 32 of 58 sides (55.2%). For this reason, we imagine that the ZT may be used as a landmark by surgeon to locate the EPs of the ILN or the laryngeal branches.