San Ildefonso Tultepec Otomi has three distinctive nasal morphemes that share a substantial number of features. The morphemes are the following: a middle marker, a detransitivizer, and a marker characterizing a closed subclass of intransitive verbs. In this article, I propose an analysis that relates these three morphemes diachronically, and links them to a common source. My analysis is able to account for both the commonalties and differences among the three morphemes. In the article, I claim that the middle marker in Otomi emerged from the reanalysis of an old inflectional morpheme characterizing a subclass of intransitive verbs depicting activities performed by humans. This analysis has important theoretical implications for the understanding of middle voice morphemes, given that, up until now, reflexives have been the only well known source for the emergence of middle markers.