Which muscle runs the length of the forearm and does not cross the wrist joint?

• A. Brachioradialis
• B. Flexor digitorum superficialis
• C. Extensor digitorum
• D. Pronator teres

Answer: (A)

The key idea is identifying a muscle that travels the full length of the forearm yet doesn’t cross the wrist joint. The brachioradialis fits this pattern: it starts high on the humerus at the lateral side and extends down the forearm to insert on the distal radius near the wrist, but its tendon stays above the wrist and does not cross the wrist joint. Because of this, it acts mainly at the elbow, flexing the forearm especially when the forearm is in a midprone/midpronation position.

In contrast, the flexor digitorum superficialis and extensor digitorum have tendons that cross the wrist to reach the fingers, so they do cross the wrist joint. The pronator teres runs across the proximal forearm and toward the radius but doesn’t span the entire forearm length, and its primary role is pronation rather than acting along the full forearm.