What is the function of the pectinate muscle?

What is the function of the pectinate muscle?

• A. Entrance to the right atrium
• B. Muscle ridges located on the internal wall and auricle of the right atrium
• C. Drainage veins
• D. Anchor chordae tendineae

Answer: (B)

Pectinate muscles are comb-like ridges of atrial muscle on the inner wall of the right atrium, especially in the atrial appendage. Their main role is to increase the contractile surface area of the atrial wall, helping the atrium squeeze blood more effectively into the right ventricle during atrial systole. They also help create the rough-walled part of the atrium, distinct from the smooth-walled portion separated by the crista terminalis. These muscles aren’t involved in forming an inlet to the atrium, draining veins, or anchoring the chordae tendineae, which relate to other structures in the heart.

Pectinate muscles are comb-like ridges of atrial muscle on the inner wall of the right atrium, especially in the atrial appendage. Their main role is to increase the contractile surface area of the atrial wall, helping the atrium squeeze blood more effectively into the right ventricle during atrial systole. They also help create the rough-walled part of the atrium, distinct from the smooth-walled portion separated by the crista terminalis. These muscles aren’t involved in forming an inlet to the atrium, draining veins, or anchoring the chordae tendineae, which relate to other structures in the heart.