On the right half of the larynx of a 35-year old man a branch of the ramus externus nervi laryngei superioris was described that entered the inner larynx without vessels through a foramen thyroideum. A foramen thyroideum that appears in adults in more than a quarter of the cases is considered on the one hand as a remaining cleft between the fused cartilagineous skeletal elements of the forth and fifth viszeral arch and on the other hand as a occasionally remaining opening on account of a vessel or nerve running through. In more than half the cases vessels and nerves together pass through a foramen thyroideum and in a further third vessels only. If, in the case described, a nerve only passes through the foramen, this nerve, in human beinges, cannot be the nerve of the fifth veszeral arch on account of phylo-and ontogenetic considerations.