Ligamentum aeriosum is derived from:

Ans. A: Ductus aeriosusThe ductus aeriosus represents the distal poion of the sixth left aoic arch and connects the left pulmonary aery to the beginning of the descending aoa.During fetal life, blood passes through it from the pulmonary aery to the aoa, thus bypassing the lungs.After bih, it normally constricts, later closes, and becomes the ligamentum aeriosum.A persistent patent ductus aeriosus results in high-pressure aoic blood passing into the pulmonary aery, which raises the pressure in the pulmonary circulation.A patent ductus aeriosus is life threatening and should be ligated and divided surgically.