part of attached to receives synaptic input from neuron labrum haustellum proboscis muscle 5 motor neuron proboscis muscle 5 2022-07-05T13:30:44Z proboscis muscle m5 Short muscle that inserts on the wall of the labrum. It is attached to the wall of the pharynx and is positioned to open the pharynx as it contracts (McKellar et al., 2020). It is synapsed by the proboscis muscle 5 motor neuron (McKellar et al., 2020). fly_anatomy.ontology labral compressor muscle dilators of labrum-epipharynx labral muscle 5 FBbt:00058791 haustellum muscle adult pharynx muscle