During the end of the 3rd week of development, vasculogenesis occurs in the paraxial mesoderm. Vessels form between developing somites and join with the dorsal aorta to form intersegmental arteries. The ventral branches of the intersegmental vessels in the thoracic region develop into the intercostal arteries. The superior intercostal artery is derived from the 7th and 8th intersegmental arteries (Schoenwolf et al. 2020; Gailloud 2014).