MaleMusFIG 31: Innervation of the protractor muscles.

A. Low power electron micrograph featuring the coupling of the protractors and anal depressor, transverse view. (Image source: N2Y [MRC] 45.)
B. Detailed view of boxed region in A showing synapses and gap junction. (PAG) Pre-anal ganglion; (v/dspL/R) ventral and dorsal spicule protractors.