Which muscle inserts into the radial tuberosity?

Which muscle inserts into the radial tuberosity?

• A. Biceps Brachii
• B. Brachialis
• C. Brachioradialis
• D. Pronator Teres

Answer: (A)

The important idea here is where a muscle attaches and how that dictates its action. The tendon of the biceps brachii inserts onto the radial tuberosity on the radius. From that position, when the biceps contracts, it pulls on the radius to flex the elbow and, especially when the forearm is supinated, helps rotate the radius to turn the palm up. The other muscles attach elsewhere: the brachialis inserts on the ulna (not the radius) and is a primary elbow flexor without affecting rotation; the brachioradialis attaches to the distal radius near the wrist and mainly acts to flex the elbow in a partially pronated/supinated position; the pronator teres inserts on the mid-radius and ulna to produce pronation, not to the radial tuberosity.

The important idea here is where a muscle attaches and how that dictates its action. The tendon of the biceps brachii inserts onto the radial tuberosity on the radius. From that position, when the biceps contracts, it pulls on the radius to flex the elbow and, especially when the forearm is supinated, helps rotate the radius to turn the palm up.

The other muscles attach elsewhere: the brachialis inserts on the ulna (not the radius) and is a primary elbow flexor without affecting rotation; the brachioradialis attaches to the distal radius near the wrist and mainly acts to flex the elbow in a partially pronated/supinated position; the pronator teres inserts on the mid-radius and ulna to produce pronation, not to the radial tuberosity.