What is the primary function of the biceps tendon?

What is the primary function of the biceps tendon?

• A. Extend the shoulder and flex the elbow
• B. Extend the elbow and rotate the forelimb
• C. Flex the shoulder and extend the elbow
• D. Adduct the limb at the shoulder

Answer: (A)

The biceps tendon belongs to a muscle that spans two joints, so its actions occur at both the elbow and the shoulder. Its primary effect at the elbow is flexion (bringing the forearm toward the upper arm) and it also contributes to forearm supination. The long head that crosses the shoulder can influence shoulder movement as well, and in many contexts this joint-level action is described as assisting in extending the shoulder when the elbow is flexed or when the limb is bearing weight. For this item, the idea is that the tendon’s role includes extending the shoulder while flexing the elbow, which fits the dual-joint nature of the tendon. The other options describe actions not primarily produced by the biceps tendon—elbow extension, forearm rotation (as a primary action), or shoulder adduction—so they don’t align with how the biceps tendon functions.

The biceps tendon belongs to a muscle that spans two joints, so its actions occur at both the elbow and the shoulder. Its primary effect at the elbow is flexion (bringing the forearm toward the upper arm) and it also contributes to forearm supination. The long head that crosses the shoulder can influence shoulder movement as well, and in many contexts this joint-level action is described as assisting in extending the shoulder when the elbow is flexed or when the limb is bearing weight. For this item, the idea is that the tendon’s role includes extending the shoulder while flexing the elbow, which fits the dual-joint nature of the tendon. The other options describe actions not primarily produced by the biceps tendon—elbow extension, forearm rotation (as a primary action), or shoulder adduction—so they don’t align with how the biceps tendon functions.