There is anatomical and histological evidence for three functionally distinct muscle bellies in the canine posterior cricoarytenoid (PCA) muscle. This study attempted to define the exact nerve branching pattern to each muscle belly in 10 dogs using a modification of Sihler's neural staining technique. The results are presented here as photographs and schematic nerve maps which illustrate the following points. 1. the final terminal branches within the PCA do correspond to the three bellies of the PCA; 2. the initial nerve branch to the PCA is usually composed of multiple fascicles which rearrange before their final branching to the three bellies; 3. there is tremendous variability of the nerve branching patterns including bilateral asymmetry within the same animal; 4. the terminal branching within each belly can be surprisingly complex and contain multiple anastomoses; 5. the fast- and slow-twitch bellies of the PCA have different terminal branching patterns. These results support the functional subdivision of the canine PCA into three distinct neuromuscular compartments. This microanatomical technique appears useful for studying the basic neuromuscular organization of laryngeal muscles and their developmental and pathological changes.