The veins of the heart consist of one large vein, the =vena cordis
magna=, and a number of small veins.
=Vena cordis magna= (Fig. 118, 3).--This arises as a number of scattered
branches on the surface of both ventricles. These unite to form two main
trunks. One of these, on the ventral side of the heart, marks externally
the septum between the two ventricles. It passes beneath the left
auricular appendage, then turns to the left and passes along the sulcus
coronarius to the dorsal side of the heart. Here it unites with the
second main trunk which ramifies over the surface of the left ventricle.
Arriving at the base of the right auricle it enters this by the coronary
sinus, which lies just beneath the opening of the inferior vena cava.
In addition to the vena cordis magna and its branches there are a number
of small veins, especially in the wall of the right ventricle. These
enter the right auricle by a number of small separate openings along the
sulcus coronarius.