Has been classified as an indirect flight muscle (Dickinson and Tu, 1997), although authors say this is arbitrary - it does not connect to a wing sclerite, but does insert within the wing hinge. Classified as a tension muscle by Wisser and Nachtigall (1984). Trimarchi and Schneiderman (1994) state that this is a single muscle bundle in D. melanogaster, but dorsal and ventral parts are referred to as tergopleural 1 and 2, respectively by O'Sullivan et al. (2018).