Zuckerkandl's tubercle of the thyroid gland: Its location in the anatomical position, and comparative morphology of the same specimens before and after fixation.

The aim of this study was to elucidate the definition of the borders and surface of the thyroid lobe in the anatomical position, and to compare the morphology of Zuckerkandl's tubercle (ZT) in the fresh and fixed states. One hundred thyroid lobes from 50 fresh Korean cadavers were used. The lateral border of the thyroid lobe could be defined as the most lateral margin of its anterior aspect when in the anatomical position. The posteromedial border was the margin that projected toward the trachea or tracheoesophageal groove. The lateral and posteromedial borders, and the posterior surface between these borders, could be identified in most of the fixed cadavers. The posterolateral border could only be identified in the thyroid lobe if there was compression by the internal carotid artery in cross-sectioned specimens and CT images. The ZT was identifiable in 85% of both fresh and fixed specimens. It was identified mainly at the posteromedial border of the thyroid lobe when in the anatomical position, and extended to the tracheoesophageal groove or esophagus. In the fresh state, the ZT projected as a rounded cone with a usually semicircular base, but its shape was very variable in the fixed state. In the present study, the ZT was found at the posteromedial border or posterior surface of the thyroid lobe in both the fresh and fixed states, contrary to most previous reports. The location of the ZT should be established in the anatomical position to avoid confusion.