The failure to divide the single artery in the embryo stage which would be the aorta and pulmonary arteries.
The truncus arteriosus can be seen to leave the ventricle and lie beneath the digestive tract. Farther forward the truncus loses much of its musculature and becomes a blood vessel, the ventral aorta.
A single artery (truncus) arises from the base of the heart because of failure of proximal division into the aorta and the pulmonary artery. Thus, both pulmonary and systemic arteries as well as the coronary arteries arise from the common trunk. Truncus arteriosus is divided into two types depending on whether there is a VSD or an intact ventricular septum. syn. common arterial trunk.
The truncus arteriosus and bulbus cordis are divided by the aorticopulmonary septum.