Interior of right atrium and ventricle with aortic and pulmonary valves
In specimen 2 we can identify the Superior vena cava and Inferior vena cava draining into the into right atrium. We can also see the opening of coronary sinus into the right atrium. The interior of the right atrium is exposed and the fossa ovalis along with the limbus fossa ovalis can be appreciated. In the interior of right ventricle, we can see the papillary muscles attached to the tricuspid valve with the help of chordae tendinae.
In specimen 3, we can see the ridge, i.e., crista terminalis. We can also see the muscular elevations which are the musculi pectinate extending from the crista terminalis. The opening of coronary sinus into the right atrium and the fossa ovalis in the inter-atrial wall are also visualized.
The aortic orifice is an opening that is present at the junction where the aortic vestibule continues as the ascending aorta. It is guarded by a tricuspid semilunar valve. The three cusps form aortic sinuses. The anterior aortic sinus from which arises the right coronary artery. The left posterior aortic sinus gives origin to the left coronary artery. The right posterior aortic sinums is a non-coronary sinus.
The pulmonary orifice is an opening that is present at the junction where the right ventricular infundibulum continues as the pulmonary trunk. It is guarded by a tricuspid semilunar valve
Superior vena cava:
A large vein draining the upper part of the body. It is formed by the union of the right and left brachiocephalic veins. It is valveless and opens into the upper part of the right atrium.
Inferior vena cava:
A large vein draining the lower part of the body. It is formed by the union of the right and left common iliac veins. It opens into the right atrium and is guarded by the Eustachian valve.
Coronary sinus is the main vein of the heart. It lies in the left atrioventricular groove and open into the right atrium. It is guarded by the thebasian valve.
Fossa ovalis and Limbus fossa ovalis:
The fossa ovalis is seen in the inter-atrial wall/septum. It is a remnant of septum primum. Its crescent margin is the limbus fossa ovalis which is a remnant of septum secundum.
Part of the trabeculae carneae of the ventricles (also called pillars). There are three papillary muscles on the right (anterior, posterior and septal) and two (anterior and posterior) on the left. These pillars provide thread like projection called the chordae tendinae that are attached to the cusps of the atrioventricular valves (tricuspid and biscupid).
The tricuspid valve guards the right atrioventricular orifice. It is made of three cusps or leaflets that are attached to the papillary muscles by the chordae tendinae.
Thread like structures extending from the papillary muscles and attached to the cusps of the atrioventricular valves.
It is a prominent ridge present in the interior of the right atrium extending from the opening of the superior vena cava to the opening of the inferior vena. It corresponds to the sulcus terminalis in the exterior of the heart that runs along its right margin. It gives rise to muscular ridges called musculi pectinati.
They are transverse muscular ridges arising from the crista terminalis. In the auricle the muscular ridges are interconnected to form a network.