The incidence and distribution of landmarks relating to the coronary sinus (c.s.) were evaluated in 240 human hearts. Special attention wasdirected to the myocardial coat of the c.s., the distribution and pattern of the cardiac veins, and their dimensions. In all specimens the myocardial coat of the C.S. also covered the adjacent 2 to 11 mm of the great cardiac vein. In 15% of cases this myocardial layer was thickened in a sphincter-like fashion, the edge of which was formed obliquely, in a crescent-like manner, or diffusely without a sharp border.In 3% of the hearts the myocardial cover of the C.S. extended over the terminal 10 mm of the middle cardiac vein as a strong fiber cord. In 9%, single isolated belts of fibers fixated the terminal parts of the adjoining cardiac veins to the posterior wall of the left atrium, and in 8% two or three myocardial cords, embedded in the fatty tissue of the left coronary sulcus, did the same.Because the myocardial cover extended leftwards to variable distances over the c.s., the left edge of the myocardial covering cannot serve to define the beginning of the coronary sinus. The location of the ostial valve of the great cardiac vein (valve of Vieussens) was variable as well, being found on the average 2.5 mm proximal to the opening of the oblique vein of the left atrium. Moreover, the valve of the great cardiac vein was found in only 87% of cases; therefore it is inappropriate for defining the beginning of the coronary sinus. Finally, the dot-like ostium of the oblique vein was most constant, and from the viewpoint of embryologic development, it is the logical landmark for determining the beginning of the coronary sinus, a necessary presupposition for cardiologic procedures like reperfusion of cardiac veins.

Modern anatomical description divides the cardiac veins into two groups: tributaries of the greater cardiac vascular system (GCVS) and tributaries of the smaller cardiac vascular system (SCVS), consisting of the Thebesian vessels. Both systems intercommunicate extensively. With the exception of the oblique vein of the left atrium (Marshall's vein), veins draining the walls of both the left and right atrium have not been well illustrated or described in anatomical atlases and textbooks. Consequently, we do not know exactly to which of the two groups (GCVS or SCVS) the atrial veins belong. There are three groups of left atrial veins: (1) tributaries of the left coronary vein and the coronary sinus; (2) special veins draining the right-sided walls of the left atrium that terminate via intramural sinuses in the right atrium, which vessels occur in 92% of cases and belong to the GCVS; (3) in 81% of cases special veins drain the myocardium of the posterior and superior walls of the left atrium. In most cases they empty into the left atrium itself; in almost 40% of the cases they are connected with mediastinal veins. These veins, also belonging to tributaries of the GCVS, constitute a distinctly separate category of cardiac veins and should be designated proper veins of the left atrium. The veins draining the walls of the right atrium fall also into three groups: (1) In most cases there are short or large intramural tunnels or sinuses in the basic walls of the auricle and atrioventricular node area. The generally valveless openings of all the venous tunnels and sinuses are lined up on a circle just above the tricuspid valve and between the openings of both venae cavae. (2) There are also thin veins at the junction of the right atrium with both the superior and inferior vena cava. (3) In addition, there are numerous cardiac veins of the "smallest size" (real Thebesian veins).

Described are: 1. Length and width values of the rhomboid fossa. 2. Number and development of the transverse and oblique striae in the bottom area of the fourth ventricle. 3. The course of the facial nerve inside the pons and the medulla oblongata. 4. Some fiber tracts and nuclei in the tegmentum pontis and the medulla oblongata. 5. A very thick arcuato-cerebellar tract. 6. The results of our investigations are compared with descriptions of other researchers.

In the human heart, anterior and posterior septal branches are mainly responsible for the arterial supply of the interventricular septum. These arteries are the basis of efficient intercoronary collateralization. The right and left superior septal arteries also contribute to the nourishment of the septum and to any eventual collateralization. Because the right superior septal artery (RSSA) is small in diameter, short, and has a variable origin either at the proximal stem or in the ostial area of the right coronary artery, it is difficult or almost impossible to visualize it angiographically. During investigation of the arterial supply of the interventricular septum in 84 human heart specimens and 16 corrosion casts, we found a few peculiarities in the origin and pattern of the RSSA in four specimens. The RSSA was found in 27 cases (27%); in most it was a single vessel and arose from three different locations: (a) the proximal part of the right coronary artery (21 cases); (b) the right coronary ostial area (four cases); and (c) from the floor of the right (anterior) aortic sinus (two cases). Macroscopically, in 16 cases the RSSA had a length of less than 10 mm; in nine cases the arteries were between 11 and 17 mm long. In two cases the RSSA was of more substantial appearance and up to 36 mm in length; it nourished almost the entire upper third of the septal myocardium. In these two cases, two courses could be differentiated: an extramural course with the RSSA descending to the subvalvular fibrous tissue, and an intramural course with ramification in the myocardium of the crista supraventricularis and the superior parts of the interventricular septum. One cadaveric heart specimen and one corrosion cast showed RSSAs that originated "early" (ectopically) on the floor of the right (anterior) aortic sinus; their total lengths were 16 and 17 mm, respectively. Such ectopic ostia of RSSAs have never been described before in the anatomical literature. Given the intense clinical concern with the identification of possible bypass vessels in the myocardium, we assume that the RSSA may have a potential as a collateral route. These findings were also discussed in light of developmental and comparative anatomy.