The Anatomical and Clinical Significance of the Superior Laryngeal Nerve

Objective This study summarizes the anatomical features of the superior laryngeal nerve in Chinese to enable the rapid location of the superior laryngeal nerve during an operation. Study Design Retrospective analysis of anatomical data. Setting Hangzhou First People's Hospital Affiliated to Nanjing Medical University. Methods A total of 71 embalmed human cadavers (132 heminecks) were examined over 3 months. The length and diameter of the internal and external branches of the superior laryngeal nerve and their relationships with different landmarks were recorded. Results The total length of the internal branch of the superior laryngeal nerve was 23.4 +/- 6.9 mm. The length of the external branch of the superior laryngeal nerve was 47.7 +/- 11.0 mm. Considering the midpoint of the lower edge of the thyroid cartilage as the starting point and using that edge as a horizontal line, when the entry point is above that line, the external branch of the superior laryngeal nerve can be found within 41.1 mm and at an angle of 57.2 degrees. When the entry point is below the lower edge of the thyroid cartilage, the external branch of the superior laryngeal nerve can be found within 34.0 mm and at an angle of 36.5 degrees. Conclusion The superior laryngeal nerve in Chinese people has distinct anatomical characteristics. This article provides a new method of quickly locating the external branch of the superior laryngeal nerve during the operation, which can reduce the probability of damaging the external branch of the superior laryngeal nerve.