heart right atrium morphology trait atrioventricular node morphology trait Any measurable or observable characteristic related to the shape, structure, color or pattern of the small nodular mass of specialized muscle fibers located in the interatrial septum near the opening of the coronary sinus; this node gives rise to the electrical connection between the atria and ventricles and responds to the sinoatrial node. Trait.ontology VT:0004114 impulse conducting system morphology trait