Which of the following muscle pairs is INCORRECT?

• A. Smooth muscle: Involuntary
• B. Chest: Axial and Appendicular muscles
• C. Skeletal muscle: Diaphragm
• D. Skeletal muscle: Striations

Answer: (C)

Understanding muscle classification helps you see why this pairing isn’t actually incorrect. The diaphragm is a skeletal muscle, meaning its fibers are striated and it is innervated by a motor nerve (the phrenic nerve). Even though breathing is largely automatic, that automatic control doesn’t change the tissue type of the diaphragm; it remains a skeletal muscle. So labeling the diaphragm as a skeletal muscle is accurate. The other pairings align with general truths too: smooth muscle is involuntary, and chest muscles are considered part of the axial region rather than purely appendicular, while skeletal muscles are characteristically striated. If a question seems to mark this as incorrect, it may reflect a keying quirk, but the anatomical classification supports the diaphragm as a skeletal muscle.