Anatomically speaking, the heart model primarily shows the 4 chambers, the auricles, the heart's blood supply (arteries and veins), the 4 valves based on the sac valve and flap system, the beginning of the blood vessels that carry blood to and from the heart as well as neat details of the heart's structure ( i.e. endo-, myo- and pericardium). The heart's impulse conduction system is not seen.
Generally speaking, the structure of the heart consists of 3 layers: Endocardium (a thin endothelial-covered connective tissue), myocardium (the thick muscle) and epicardium at the outer end, which is a serous membrane. In the ventricles, the structure is extremely complex, because the myocardium is made up of muscular muscle bundles, which run downward (and back again) in spiral-like shapes. This results in the ventricles shortening during a contraction (during the pumping action).
If the front of the heart model is removed, the complex muscular structure of the ventricles is clearly seen. Furthermore, the inner surfaces of the ventricles are made up of protruding muscle ridges (trabeculae carneae), which cross each other at different angles. This can be seen particularly clearly on the heart model.
The 2 AV valves (between atria and ventricles) are tied to papillary muscles in the ventricles, which is also very clear on the model.
