What is the name given to the portion of the right ventricle before the pulmonary trunk begins?

What is the name given to the portion of the right ventricle before the pulmonary trunk begins?

• A. Tricuspid valve
• B. Conus arteriosus or Infundibulum
• C. Sinus venosus
• D. Papillary muscle

Answer: (B)

The right ventricle has an inflow portion with trabeculae and a smooth-walled outflow tract that leads into the pulmonary trunk. That smooth-outflow segment is the conus arteriosus, also called the infundibulum. It forms the funnel-shaped passage just before the pulmonary valve, directing blood into the pulmonary trunk. The crista supraventricularis marks the border between the inflow (trabeculated) region and this outflow portion. The other structures listed aren’t the part of the ventricle that transitions into the pulmonary trunk: the tricuspid valve lies at the atrioventricular boundary, the sinus venosus is an embryologic precursor of part of the right atrium, and papillary muscles are inside the ventricle supporting the AV valve leaflets.

The right ventricle has an inflow portion with trabeculae and a smooth-walled outflow tract that leads into the pulmonary trunk. That smooth-outflow segment is the conus arteriosus, also called the infundibulum. It forms the funnel-shaped passage just before the pulmonary valve, directing blood into the pulmonary trunk. The crista supraventricularis marks the border between the inflow (trabeculated) region and this outflow portion. The other structures listed aren’t the part of the ventricle that transitions into the pulmonary trunk: the tricuspid valve lies at the atrioventricular boundary, the sinus venosus is an embryologic precursor of part of the right atrium, and papillary muscles are inside the ventricle supporting the AV valve leaflets.