Anatomic study of human laryngeal ganglia: number and distribution.

We have studied 12 laryngeal nerves: six internal branches of the superior laryngeal nerve (ILN) and six recurrent laryngeal nerves (RLN) from three human adult larynges (two males and one female). After dissection of each individual laryngeal nerve using a surgical microscope, the nerves were preserved in 10% formalin, embedded in paraffin wax, serially sectioned transversely at a thickness of 10 microm and stained with hematoxylin and eosin. We found 2-4 ganglia associated with the ILN. At least two ganglia were always present (six out of six cases), the largest one being associated with the branch of the nerve innervating the vestibule and the smallest one associated with the branch innervating the aryepiglottic fold. Other ganglia were found associated with the branches for the glosso-epiglottic fold and vallecula (four out of six cases) and interarytenoid muscle (three out of six cases). The RLN showed from two to six ganglia, all of them located in its anterior terminal division. Two of the ganglia were located in the part of the nerve between the origin of the branches for the interarytenoid and lateral cricoarytenoid muscles (three out of six cases). The remaining ganglia were located close to or at the origin of the muscular branches innervating the intrinsic laryngeal muscles. The cytology of the ganglia reported suggests that they were all autonomic in nature, probably parasympathetic.