Final answer:
The septum that partitions the bulbus cordis is part of the interventricular septum, which is a thick, muscular wall separating the two ventricles and reinforced by the cardiac skeleton.
Step-by-step explanation:
The septum that partitions the bulbus cordis is not specifically named in the provided information, but the bulbus cordis develops into the right ventricle of the heart. Thus, the relevant septa related to the bulbus cordis would be the interventricular septum, which separates the two ventricles. The structure of this septum is characterized by being a thick, muscular wall that is heavily reinforced with dense connective tissue known as the cardiac skeleton.
The interventricular septum is substantially thicker than the interatrial septum because it must withstand the greater pressure exerted by the ventricles as they contract to pump blood. It is a physical extension of the myocardium (the heart muscle) lined with endocardium (the inner layer of heart tissue).