]> TN innervated muscle cell of A1-7 The classification of muscles in SN, ISN or TN innervated is based not only on innervation, but also orientation (and presumed function), specification pathways during development (wingless dependendence for SN and TN innervated muscles) and the muscle's location in the internal or external layers (although there are exceptions to this) (Landgraf et al., 1997). fly_anatomy.ontology external muscle cell FBbt:00110303 Any muscle cell (FBbt:00005074) that is part of some TN innervated muscle of A1-7 (FBbt:00059152). 2013-02-19T10:52:34Z hypodermal muscle cell of A1-7 larval TN motor neuron part of TN innervated muscle of A1-7 muscle cell receives synaptic input from neuron