Injury of the external branch of the superior laryngeal nerve (EBSLN) is the most neglected complication of thyroidectomy, and is mainly characterized by vocal cord fatigue and a reduced frequency range of the vocal cords [1]. Unlike recurrent laryngeal nerve (RLN) injury, EBSLN injury does not affect vocal cord movement, does not show standard electronic laryngoscopic changes, and causes minor changes to the voice [2,3]. However, in patients with occupations that require extensive voice use (such as salespeople, teachers, singers, and announcers), this type of injury seriously affects their quality of life and professional ability. The incidence of EBSLN injury during thyroidectomy has been reported to be as high as 60% in some studies [4,5] as the anatomic variation of the EBSLN is large and the nerve itself is thin. In the past, the circumvention method was used to reduce the rate of injury to the EBSLN, but its effect was poor [6].

In order to effectively reduce iatrogenic injury to the EBSLN, many surgeons have increasingly come to pay attention to the anatomical characteristics of the EBSLN and use relevant surgical skills and nerve monitoring techniques to expose and protect it to effectively avoid injuring it. Studies have shown that neuromonitoring technology can greatly reduce injury to the EBSLN [[7], [8], [9], [10]], but due to the widespread lack of the necessary equipment and its high cost, many thyroid surgeons find it difficult to use this technology indiscriminately in thyroidectomy. Thus, our team aimed to expand the triangular region as much as possible and standardize the exploration process of the EBSLN in terms of the sternothyroid-laryngeal triangle's anatomical characteristics, with the goal of using visual techniques to minimize damage to the EBSLN.