ABSTRACT. Distributions of the cardiac plexuses and cardiac ganglia were gross-anatomically and histologically studied in eight Beijing ducks. The cardiac plexuses consisted of two components, the cardiac nerve arising from the sympathetic trunk and the cranial and caudal cardiac nerves arising from the vagus. Branches of these nerves made the cardiac plexuses on the epicardium. The cardiac plexuses could be divided into the six plexuses, that is, the right and left coronary plexuses, pericardiac transverse sinus plexus, caudal cardiac plexus, and right and left superior cardiac plexuses. There were small ganglia in the caudal cardiac plexus and the right and left coronary plexuses. These ganglia containing multipolar neurons were found like a linking chain in a single nerve. -KEY WORDS: Beijing duck, cardiac ganglion, cardiac plexus.J. Vet. Med. Sci. 59(5): 409-411, 1997 anastomosing with each other. The trunk of the left sympathetic cardiac nerve (Fig. 1a, b-1') ran caudomedially to the surface of the left cranial vena cava (Fig. 1a, b-F'), and ramified into two or three branches. These branches anastomosed with the left caudal cardiac nerves of the vagus (Fig. 1a, b-4'). The right sympathetic cardiac nerve ( Fig. 1c-1) gave off two branches after arrival at the base of the heart. One branch ran along the dorsolateral surface of the right cranial vena cava (Fig. 1c-F). The trunk of the right sympathetic cardiac nerve ran obliquely and caudally along the caudal vena cava (Fig. 1c-G), and anastomosed with the right caudal cardiac nerves of the vagus (Fig. 1c-4). On the other hand, each vagus nerve trunk gave off the left or right cranial cardiac nerve near the nodose ganglion. The left vagal cranial cardiac nerve ( Fig. 1d-3') received branches from the left sympathetic cardiac nerve, and reached the right coronary sulcus through the arterial cone. The right vagal cranial cardiac nerve ( Fig. 1d-3) descended along the dorsal surface of the right pulmonary artery (Fig. 1d-C). Further descending, the continuation of the vagus nerve trunk (Fig. 1a, b-2', 1c-2) formed a ring of the nerve near the pulmonary vein (Fig. 1a, b-E', 1c-E) through the base of the heart. The caudal cardiac nerves (Fig. 1a, arose from the ventral branch of the ring of the vagus nerve or from the vagus nerve trunk more caudally. They anastomosed with the sympathetic cardiac nerve of each side (Fig. 1a, b-1', 1c-1).The caudal cardiac plexus (Fig. 1a, b, c-5) was formed by the sympathetic cardiac nerves (Fig. 1a, b-1', 1c-1) and vagal caudal cardiac nerves (Fig. 1a, b-4, 4', 1c-4) of both sides on the dorsal surface of the atrium. It lay on the right and left atriums and basal parts of the right and left ventricles. The left superior cardiac plexus (Fig. 1b-6') was formed by the left sympathetic cardiac nerve (Fig. 1b-1') and left caudal cardiac nerves (Fig. 1b-4') of the vagus. It was distributed on the dorsal surface of the left atrium. The right superior cardiac plexus (Fig. 1b, c, d-6) was formed by three branches: one branch from the...