All of the following are true except

Options

A. Trabeculae carnae , the muscular ridges of ventricles are also known as columnae carnae
B. Musculi pectinati are present in ventricular walls
C. There are three papillary muscles in right ventricle are two in left ventricle
D. Papillary muscles are attached to AV valves through chordae tendinae

Answer

To solve the question "All of the following are true except," we need to analyze each of the statements provided and determine which one is false.

### Step-by-Step Solution:

1. **Analyze the First Statement:**
- The statement is: "Trabecular carinae, the muscular ridges of ventricle are also known as columnar carinae."
- Explanation: Trabecular carinae are indeed muscular columns found in the inner surface of the ventricles of the heart, and they are also referred to as columnar carinae.
- Conclusion: This statement is **true**.

2. **Analyze the Second Statement:**
- The statement is: "Musculi pectinati are present in ventricular valves."
- Explanation: Musculi pectinati are actually found in the atria of the heart, not in the ventricular valves.
- Conclusion: This statement is **false**.

3. **Analyze the Third Statement:**
- The statement is: "There are 3 papillary muscles in the right ventricle and 2 in the left ventricle."
- Explanation: Papillary muscles are indeed present in the ventricles, with typically three in the right ventricle and two in the left ventricle, serving to prevent backflow through the atrioventricular (AV) valves.
- Conclusion: This statement is **true**.

4. **Analyze the Fourth Statement:**
- The statement is: "Papillary muscles are attached to AV valves through chordae tendineae."
- Explanation: This is correct; chordae tendineae connect the papillary muscles to the AV valves, helping to prevent the valves from inverting.
- Conclusion: This statement is **true**.

### Final Conclusion:
After analyzing all four statements, we find that the second statement is the only false one. Therefore, the answer to the question is that the false statement is the second one: "Musculi pectinati are present in ventricular valves."