Fig. 5. The somata of the depressor motor neurons lie posterior to the neuropil. (A) Drawing of a rhodamine backfill of the depressor nerve reveals 13 somata (filled circles). For clarity only the somata are shown. The dotted line indicates the midline of the 5^th thoracic ganglion. To aid the discussion of anatomical figures that follow, we divided the neuropil into four quadrants: AL (anterior-lateral), AM (anterior-medial), PL (posterior-lateral) and PM (posterior-medial). The cell body of the common inhibitor, which lies on the midline, was not filled in this particular preparation. (B) A cross section of the depressor nerve shows 18 circular profiles, including 13 with thick walls. The five thin-walled profiles are among the smallest in diameter. (C) The diameters of the 13 thick-walled profiles vary in a continuous manner.