[TA] normal left-sided narrowing of the esophagus, demonstrated radiographically after a barium swallow, at the T4-T5 vertebral level, where the esophagus is impressed by the left main bronchus and the arch of the aorta. SYN: constrictio partis thoracicae esophagea [TA], broncho-aortic constriction*, constrictio bronchoaortica esophagea*, middle esophageal constriction.