These are coronary veins or any structure associated with coronary veins : b. Great cardiac vein, c. Coronary sinus , & d. Middle cardiac vein. The great cardiac vein (GCV) is the largest of the veins draining into the coronary sinus from the myocardium. The coronary sinus is a collection of veins joined together to form a large vessel that collects blood from the heart muscle (myocardium). The middle cardiac vein commences at the apex of the heart; ascends in the posterior longitudinal sulcus, and ends in the coronary sinus near its right extremity. While jugular veins are any of several large veins in the neck, carrying blood from the head and face.