Basic plan of Aortic arches

In typical vertebrate embryo, major arterial channels: – Ventral aorta – Dorsal aorta – 6 pairs of Aortic Arches: connecting Ventral & Dorsal aorta Blood leaves heart through ventral aorta  runs forward, midventrally, beneath the pharynx  branches anteriorly into a pair of External Carotid Arteries into head In b/w, the Ventral aorta gives off 6 pairs of aortic arches running through visceral arches Each aortic arch consists of a • Ventral Afferent Branchial Artery carrying venous blood to capillaries in a gill • Dorsal Efferent Branchial Artery taking arterial blood from the gill • All efferent branchial arteries of the same side join dorsally to form a Lateral Dorsal Aorta/ Radix • Radix extend into head as Internal Carotid Artery • The two lateral dorsal aortae unite just behind the pharynx to form a single Median Dorsal Aorta which continues behind into tail region as Caudal artery. • Branches from these main arterial channels supply all parts of the vertebrate body.