The stapedial artery passes through the ring of the stapes and divides into supraorbital, infraorbital, and mandibula branches which follow the three divisions of the trigeminal nerve.

[6] The infraorbital and mandibular branches arise from a common stem, the terminal part of which anastomoses with the external carotid artery.

The fourth right arch forms the most proximal segment of the right subclavian artery, as far as the origin of its internal thoracic branch.

[2] The proximal part of the sixth right arch persists as the proximal part of the right pulmonary artery while the distal section degenerates; The sixth left arch gives off the left pulmonary artery and forms the ductus arteriosus; this duct remains pervious during the whole of fetal life, but then closes within the first few days after birth due to increased O2 concentration.

The ductus arteriosus connects at a junction point that has a low pressure zone (commonly called Bernoulli's principle) created by the inferior curvature (inner radius) of the artery.