proximal right subclavian

Normally, the left fourth arch becomes the aortic arch, the right fourth arch contributes to the innominate artery[http://emedicine.medscape.com/article/899609-overview] in birds it is the right fourth arch which forms the permanent aorta

The fourth right arch forms the right subclavian as far as the origin of its internal mammary branch; while the fourth left arch constitutes the arch of the aorta between the origin of the left carotid artery and the termination of the ductus arteriosus[WP][Wikipedia:Aortic_arches#Arch_4]., The forth in a series paired arterial connections between the dorsal and ventral aortae, lies within the 4th branchial arch. The paired aortic arch 4 arteries branch directly from the ventral aorta to the lateral dorsal aorta, and are retained as the branchial arteries providing circulation through the gills in the adult.[AAO], Aortic arches 3 and 4 are not remodeled but are retained largely intact as the branchial arteries providing circulation through the gills. These areches are direct branches from the ventral aorta to the lateral dorsal aorta. Isogai et al. 2001.[TAO]

UBERON:0004350

uberon

4th branchial arch artery, 4th pharyngeal arch artery, 4th aortic arch artery, systemic arch

UBERON:0003121

• arch of aorta