Final answer:
The posterior division of the middle cardiac vein drains areas supplied by the posterior interventricular artery into the great cardiac vein, which is involved in cardiac circulation. The posterior auricular vein drains the region behind the ear into the external jugular vein.
Step-by-step explanation:
The posterior division of the middle cardiac vein is a vessel that parallels and drains the areas supplied by the posterior interventricular artery, commonly known as the posterior descending artery. It is significant for its role in cardiac circulation as it drains into the great cardiac vein, thus removing deoxygenated blood from the myocardium.
The posterior interventricular artery branches off from the right coronary artery and travels along the posterior portion of the interventricular sulcus towards the apex of the heart, supplying blood to the interventricular septum and parts of both ventricles.
As for the posterior auricular vein, it is not directly related to the cardiac veins but is a superficial vein located behind the ear. It drains blood from the auricular and scalp regions into the external jugular vein.