Supraventricular crest lies between-

Ans. is 'a' i.e., Pulmonary orifice and atrioventricular orifice Interior of right ventricle* It is anteroinferior chamber and projects to the left of right atrium. It is in contact with the sternum.* It is divided into -i) Rough inflowing part (ventricle proper)# It is developed from right half of primitive ventricle.# Its interior is rough due to the presence of muscular ridges known as trabeculae carneae, which are more prominent in apical region.# Trabeculae carneae are of 3 types: -1. Ridges - Linear elevations.Supraventricular crest - a ridge present between the pulmonary and atrioventricular orifices, extends downwards in the posterior wall of the infundibulum.2. Bridges -'Muscular elevations with fixed ends on ventricular walls, the center being free.Septomarginal trabecula: It is a specialized bridge which extends from the right of ventricularseptum to the base of anterior papillary muscle. It contains the right branch of atrioventricular bundle.3. Papillary muscles are conical projections of muscle fiber bundles. Their base is attached to the ventricular wall and the apex is attached to the chordae tendinae, which are further attached to the cusps of atrioventricular (AV) valves. There are three papillary muscles in the right and two in the left ventricle. They regulate closure of atrioventricular valves.ii) Smooth outflowing part (infundibulum or conus arteriosus)# Smooth outflowing part develops from mid portion of bulbus cordis and surrounds pulmonary valveSupraventricular crest (crista supraventriculars) or infundibuloventricular crest separates tricuspid (AV) orifice and pulmonary orifice, i.e. inlet and outlet parts.