Continent continent. From this perspective, the edge of the continental shelf is the true edge of the continent, as shorelines vary with changes in sea level. In this sense the islands of Great Britain and Ireland are part of Europe, while Australia and the island of New Guinea together form a continent. As a cultural construct, the concept of a continent may go beyond the continental shelf to include oceanic islands and continental fragments. In this way, Iceland is considered part of Europe and Madagascar part of Africa. Extrapolating the concept to its extreme, some geographers group the Australian continental plate
Smallest cardiac veins Therefore, the endocardial opening must be traced to a vein before it is definitely called an opening of the smallest cardiac veins. The thebesian veins are named after the German anatomist Adam Christian Thebesius, who described them in a 1708 treatise called "Disputatio medica inauguralis de circulo sanguinis in corde". Smallest cardiac veins The smallest cardiac veins (or Thebesian veins) are minute valveless veins in the walls of all four heart chambers. The veins are sometimes accurately referred to as vessels, but they are frequently confused with a distinct set of artery connections eponymously referred to as the "vessels of