[TA] of the four bronchopulmonary segments of the inferior lobes of the right or left lung that contact the diaphragm, the one lying directly inferior to the hilum of the lung in contact with the middle of the lateral aspect of the mediastinum, supplied by the medial basal segmental bronchus [B VII] and medial basal segmental (pulmonary) artery. SYN: segmentum bronchopulmonale basale mediale S VII [TA], cardiac segment, segmentum cardiacum.