Left: Whole view of the central nervous system in the blowfly Protophormia terraenovae. In flies the brain (Br) and suboesophageal ganglion (SOG) are fused, and thoracic and abdominal ganglion are fused to become the thoracico-abdominal ganglion (TAG). Right: Enlarged views of the TAG. T1 LN, T2 LN and T3 LN are nerve roots running to the forelegs, middle legs and hind legs, respectively. AN: antennal nerve Br: brain OL: optic lobe SOG: suboesophageal ganglion CN: cervical nerve CC: cervical connective T1 LN: prothoracic leg nerve T2 LN: mesothoracic leg nerve T3 LN: metathoracic leg nerve TAG: thoracic-abdominal ganglion FN: frontal nerve PtN: pterothoracic nerve (wing sensory neuron) HN: haltere nerve AbN: abdominal nerve