Which muscle on the back of the upper arm extends the elbow?

Which muscle on the back of the upper arm extends the elbow?

• A. Biceps
• B. Triceps
• C. Deltiods
• D. Abdominal muscles

Answer: (B)

Elbow extension is carried out by the triceps brachii, a muscle that runs along the back of the upper arm. When it contracts, it straightens the elbow by pulling on the forearm, increasing the angle between the upper arm and forearm. The biceps brachii sits on the front of the arm and flexes the elbow, not extends it. The deltoids are shoulder muscles involved in lifting and rotating the arm at the shoulder, while the abdominal muscles belong to the core and don’t move the elbow. So the back-of-the-arm muscle that extends the elbow is the triceps.

Elbow extension is carried out by the triceps brachii, a muscle that runs along the back of the upper arm. When it contracts, it straightens the elbow by pulling on the forearm, increasing the angle between the upper arm and forearm. The biceps brachii sits on the front of the arm and flexes the elbow, not extends it. The deltoids are shoulder muscles involved in lifting and rotating the arm at the shoulder, while the abdominal muscles belong to the core and don’t move the elbow. So the back-of-the-arm muscle that extends the elbow is the triceps.