be excitatory, inhibitory, electrical, or neuromodulatory. for any given motor neuron, determining the relative contribution of different input sources is difficult, but advances in connectomics have made it possible for fruit fly motor neurons. in the fly, motor neurons controlling the legs and wings are found in the ventral nerve cord, homologous to the spinal cord. fly motor neurons vary by over 100x in the total number of input synapses. however, each motor neuron gets similar fractions of its synapses from each premotor source: ~70% from neurons within the vnc, ~10% from descending neurons, ~3% from sensory neurons, and ~6% from vnc neurons that also send a process up to the brain. the remaining 10% of synapses come from neuronal fragments that are unidentified by current image segmentation algorithms and require additional manual segmentation to measure.