The conus arteriosus is a conical pouch formed from the upper and left angle of the right ventricle

Right ventricle

The right ventricle is one of four chambers in the human heart. It receives deoxygenated blood from the right atrium via the tricuspid valve, and pumps it into the pulmonary artery via the pulmonary valve and pulmonary trunk....

 in the chordate

Chordate

Chordates are animals which are either vertebrates or one of several closely related invertebrates. They are united by having, for at least some period of their life cycle, a notochord, a hollow dorsal nerve cord, pharyngeal slits, an endostyle, and a post-anal tail...

 heart

Heart

The heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...

, from which the pulmonary trunk arises.

A tendinous band, which may be named the tendon of the conus arteriosus, extends upward from the right atrioventricular fibrous ring and connects the posterior surface of the conus arteriosus to the aorta

Aorta

The aorta is the largest artery in the body, originating from the left ventricle of the heart and extending down to the abdomen, where it branches off into two smaller arteries...

. The conus arteriosus is also called the infundibulum

Infundibulum

An infundibulum is a funnel-shaped cavity or organ.* Lungs: The alveolar sacs of the lungs from which the air chambers open are called infundibula...

, and it is the entrance from the right ventricle into the pulmonary artery and pulmonary trunk. The wall of the infundibulum is smooth.