Applied Anatomy of Region of Thyroid Operation in Surgery

Objective To introduce anatomic landmark for location and protection of superior laryngeal nerve and recurrent laryngeal nerve in thyroid surgery. Methods Peri-thyroid region were dissected in 100 cadaver cervical part with regard to location observation of trunks and branches of superior laryngeal nerve and recurrent laryngeal nerve. Results ① Superior laryngeal nerve gave off two branches on the outer side of superior constrictor of pharynx, the internal branches pierced the thyroid membrane into laryngeal in company with the superior laryngeal artery, the external branches descended along with superior thyroid artery posterointeriorly. ② Right recurrent laryngeal nerve ran anterior to inferior thyroid artery, posterior to inferior thyroid artery, between the arterial branches and climbing along the artery were observed in 48(48%),24(24%),14(14%) and 14(14%)cases respectively, whereas the left recurrent laryngeal nerve were observed in 15 (15%),57(57%),15(15%)and 13(13%) cases respectively. ③ The recurrent laryngeal nerve cross the thyroid in 19 branches (9.5%)at the very level of the low pole of thyroid, in 117 branches (58.5%) at the level of (9.9±7.3)mm superiorly, and in 64 branches (32%)at the level of (8.5±5.6)mm inferiorly. ④ The anterior branch of recurrent laryngeal nerve pierced into larynx distantly (7.4±3.7)mm from cornu inferior cartilaginous thyroidean, including (1.6±0.8)mm anteriorly in 72 sides (36%), (1.8±0.5)mm posteriorly in 58 sides (29%), right inferiorly in 70 sides (35%). The posterior branch of recurrent laryngeal nerve pierced into larynx distantly (7.3±3.2)mm from cornu inferius cartilaginis thyroideae, including(1.7±0.9)mm anteriorly in 16 sides (8%), (1.8±1.2)mm posteriorly in 134 sides (67%),right inferiorly in 50 sides (25%). Conclusion The superior thyroid artery must be ligated near the upper pole of thyroid, whereas the inferior thyroid artery must be cautiously identified and isolated before ligation to avoid the iatrogenic injury of recurrent laryngeal nerve and the branches.