Creating a clinical and anatomical classification of the heart is one of the most difficult sections of cardiac anatomy. The reasons for this state of affairs include insufficient development of the histostructure of the heart, limited data on the microscopic similarities and differences between the membranes of the heart and surrounding tissues, and the lack of precise anatomical basis for classifying the membranes. Unfortunately, the classification of the membranes of the heart according to morphological features remains unsatisfactory.