Which muscle extends the arm at the elbow?

Which muscle extends the arm at the elbow?

• A. Triceps
• B. Biceps
• C. Hamstrings
• D. Gastrocnemius

Answer: (A)

Extending the arm at the elbow means straightening the elbow so the forearm moves away from the upper arm. The muscle that does this is the triceps brachii, located at the back of the upper arm. When it contracts, it pulls on the ulna to straightened the elbow, acting as the elbow extensor. By contrast, the biceps brachii and other elbow flexors shorten to bend the elbow, so they don’t produce extension. The hamstrings and gastrocnemius are leg muscles that act on the hip/knee and knee/ankle, respectively, not the elbow. So the triceps is the one that extends the arm at the elbow.

Extending the arm at the elbow means straightening the elbow so the forearm moves away from the upper arm. The muscle that does this is the triceps brachii, located at the back of the upper arm. When it contracts, it pulls on the ulna to straightened the elbow, acting as the elbow extensor. By contrast, the biceps brachii and other elbow flexors shorten to bend the elbow, so they don’t produce extension. The hamstrings and gastrocnemius are leg muscles that act on the hip/knee and knee/ankle, respectively, not the elbow. So the triceps is the one that extends the arm at the elbow.