Based upon the dissection findings of 60 cadavers (120 sides)

the incidence of superior laryngeal nerve loop

connecting between cervical sympathetic chain and superior laryngeal nerve as well as its branches is 98.3%(118 out of 120 sides). In most cases

the loop connected the external laryngeal branch with the sympathetic chain. The shape of external laryngeal branch is looped

but not as traditional linear. The loop is one of the origins of thyroid nerve. The loop can be divided into three categories

the shape of the letter V

U and mixed

it can be subdivided into 5 types and 17 subtypes according to their morphological variations