Ligamentum arteriosum

The ligamentum arteriosum (or arterial ligament) is a small ligament attached to the superior surface of the left pulmonary artery and the inferior surface of the proximal descending aorta. It is a nonfunctional vestige of the ductus arteriosus, a shunt in the fetal circulation. The ductus closes and becomes the ligament within three weeks of birth.

The ligamentum arteriosum is closely related to the left recurrent laryngeal nerve, a branch of the left vagus nerve. After splitting from the left vagus nerve, the left recurrent laryngeal nerve loops around the aortic arch posterior to the ligamentum arteriosum and then ascends to the larynx.