Clinically applied anatomy of superior laryngeal nerves and recurrent laryngeal nerves

Objectives To provide applied anatomy data to avoid the nerve damage during thyroid operation. Method 120 specimens(60 left and 60 right) of antiseptic adult corpses were examined anatomically.Results Exterior branch of superior laryngeal nerve lies between the upper edge of thyroid cartilage and the superior pole of thyroid lateral lobe, the cross section diameter is 0.6±0.2mm. The diameter of recurrent laryngeal nerve when crossing over with inferior thyroid artery is 1.4±0.4mm. The distance between the points where recurrent laryngeal nerve enters larynx and cricothyroid articulation (the inferior tip of thyroid cartilage) is 5.2±1.6mm. More recurrent laryngeal nerves go infront of inferior thyroid artery in right than in the left. In the left, they go up along the groove between trachea and esophagus. In the right, they form an angle of 17.8±8.2 degrees with the trachea-esophagus groove. Conclusion Exterior branch of superior laryngeal nerve is closely related with superior thyroid artery, while recurrent laryngeal nerve crosses over inferior thyroid artery. In operations that need to expose nerve, using trachea ersophagus groove and thyroid cartilage inferior tip as singns is an easy, safe and practical way to expose recurrent laryngeal nerve.