Reconstruction of an abnormal artery observed in an 11 mm embryo: considerations on the embryologic origin of the subclavian artery.

The retro-oesophageal right subclavian a. is a classical variant. We report the first case recognised in the embryo (11 mm subject reconstructed by Born's method). Four other adult cases are analysed (1 dissection and 3 clinical cases) and compared with 250 clinical observations of the supraaortic trunks. In the modal state it arises from the 7th arterial segment. The origin of the subclavian and vertebral aa. and the arrangement of the supraaortic trunks allow the distinction of three types, whose embryologic origin is discussed.