synaptic neuropil domain mushroom body spur VFB:FBbt_00045010 FBbt:00003696 SPU The spur is classified as a separate entity, rather than part of the pedunculus, vertical or medial lobe (Ito et al., 2014). heel of mushroom body knee of mushroom body mushroom body heel fly_anatomy.ontology Synaptic neuropil domain that is a small protrusion, lateral to the anterior end of the pedunculus. FBbt:00045010 mushroom body neuropil subdivision