The elbow flexion reflex primarily tests which muscle?

The elbow flexion reflex primarily tests which muscle?

• A. Brachioradialis
• B. Triceps brachii
• C. Biceps brachii
• D. Brachialis

Answer: (C)

The elbow flexion reflex directly tests the muscle that contracts when the reflex is elicited. When the biceps brachii tendon is struck in the antecubital fossa, stretch receptors in the biceps are activated and send a signal via the musculocutaneous nerve to the C5–C6 spinal levels, then the signal returns to the biceps causing a brisk elbow flexion. This makes the biceps brachii the primary muscle responsible for that reflex. The brachioradialis has its own reflex (tapping near the radial styloid) that also causes elbow flexion, the triceps brachii is responsible for elbow extension (tested by the triceps reflex), and the brachialis, while a strong elbow flexor, is not the primary muscle demonstrated by the standard elbow flexion reflex.

The elbow flexion reflex directly tests the muscle that contracts when the reflex is elicited. When the biceps brachii tendon is struck in the antecubital fossa, stretch receptors in the biceps are activated and send a signal via the musculocutaneous nerve to the C5–C6 spinal levels, then the signal returns to the biceps causing a brisk elbow flexion. This makes the biceps brachii the primary muscle responsible for that reflex. The brachioradialis has its own reflex (tapping near the radial styloid) that also causes elbow flexion, the triceps brachii is responsible for elbow extension (tested by the triceps reflex), and the brachialis, while a strong elbow flexor, is not the primary muscle demonstrated by the standard elbow flexion reflex.