Topographic anatomy of the ınternal branch of the superior laryngeal nerve

PURPOSE The aim of this study was to investigate the surgical and topographical anatomy of the internal branch of the superior laryngeal nerve (ibSLN) in laryngectomy patients. METHODS Patients aged 36-90 years old who underwent a total laryngectomy operation with a diagnosis of laryngeal carcinoma participated in the study. Fifteen patients who underwent a total laryngectomy operation between June 2015 and November 2016 were included in the study. A total of 29 superior laryngeal nerves (SLN) of 15 patients were studied. The position of the nerve was photographed before the thyrohyoid membrane (THM) was passed during dissection. The relationship and course of the ibSLN with respect to the superior laryngeal artery (SLA) were observed. The distance to adjacent formations and branching variants were examined along the course of the nerve. RESULTS Of the total 29 ibSLN, 17 were divided into three branches and 12 into two branches. In all cases except for one, the ibSLN course after piercing the THM was determined. The ibSLN penetrated the THM at a mean of 12.0 ± 2.61 mm (6-16 mm) from the superior border of the thyroid cartilage. The ibSLN penetrated the THM with a mean distance of 9.34 ± 1.65 (6-12) mm from the inferior border of the hyoid bone. CONCLUSION Our study demonstrated the surgical and topographical features of the ibSLN with respect to the THM, and provided a more precise knowledge of its anatomy in laryngectomy patients. It thus may help head and neck surgeons identify this nerve.