Also known as the right superior lobar bronchus, the eparterial bronchus is a branch of the right main bronchus given off about 2.5 cm. from the bifurcation of the trachea. This branch supplies the superior lobe of the right lung and is the most superior of all secondary bronchi. It arises above the level of the pulmonary artery, and for this reason is named the eparterial bronchus. All other distributions falling below the pulmonary artery are termed hyparterial. This classification is attributed to Christoph Theodor Aeby (1835–1885) and is central to his model of the anatomical lung which he presented in a monograph titled, "Der Bronchialbaum der Säugethiere und des Menschen, nebst Bemerkungen über den Bronchialbaum der Vögel und Reptilien" (Leipzig : Wilhelm Engelmann, 1880).
The eparterial bronchus is the only secondary bronchus with a specific name apart from the name of its corresponding lobe.