Opening of pulmonary trunk

The opening of the pulmonary trunk refers to the anatomical orifice where the pulmonary artery (via the pulmonary trunk) arises from the right ventricle of the heart by the conus arteriosus. The opening is guarded by the pulmonary valve, which prevents backflow during diastole

The opening is surrounded by a fibrous ring (anulus fibrosus), which forms part of the cardiac fibrous skeleton. This ring provides structural support and attachment for the pulmonary valve cusps.