Which term describes the muscular wall dividing the ventricles?

• A. Interventricular septum
• B. Papillary muscle
• C. Pectinate muscle
• D. Chordae tendinae

Answer: (A)

The wall that separates the two ventricles is called the interventricular septum. It is mainly muscular, forming the thick partition between the right and left ventricles, with a small membranous portion near the top. This separation keeps the oxygen-poor blood in the right ventricle from mixing with the oxygen-rich blood in the left ventricle. The muscular part is especially thick on the left side because the left ventricle must generate higher pressure to pump blood systemically. Among related structures, papillary muscles and chordae tendineae are involved with valve function inside the ventricles, and pectinate muscles are ridges found in the atria, not the ventricles.