BACKGROUND

The abundance of various anatomical classifications of the external branch of the superior laryngeal nerve in literature sources indicates the absence of universal landmarks for its intraoperative visualization. Therefore, the external branch of the superior laryngeal nerve still remains «undeservedly unnoticed» by many surgeons during thyroidectomy. However, injury of the external branch of the superior laryngeal nerve is associated with the loss of the ability to produce high-frequency sounds, the appearance of hoarseness, vocal fatigue, dysphagia, which can significantly worsen the patient’s life quality.

OBJECTIVE

The purpose of this work is a precision research of the special anatomical region, identifying landmarks for intraoperative monitoring of the external branch of the superior laryngeal nerve.

MATERIAL AND METHODS

In this study we identify 60 external branches of the superior laryngeal nerve in cadaver neck organ complexes.

RESULTS

According to our analysis of all anatomical pictures, the tendinous arch of inferior pharyngeal constrictor muscle and the oblique line of thyroid cartilage are permanent, constant, easy to visualize, and close localized anatomical landmarks for identification the external branch of the superior laryngeal nerve. These anatomical structures confine a small fascial-muscular triangular space usefulfor surgical orientation. We have classified four anatomical types of the external branch of the superior laryngeal nerve. In 59.4% of cases (type I and type II) the branches located in close proximity to the upper pole of the thyroid gland and the site of upper thyroid vessels ligation. Type III and type IV (40.6% of cases) of the external branch of the superior laryngeal nerve were covered on all extent by the fibers of the inferior pharyngeal constrictor muscle, and the «entry» point of the nerve was located far from the upper pole of the thyroid gland.