Question

What is the function of the muscle shown in the picture?

• A. Flexion
• B. Extension
• C. Adduction
• D. Abduction

Hint:

Lumbricals flex the MCP joints (the writing position).

Answer 1

The Correct Option is A

Step 1: The muscle in the image is one of the lumbricals, four small intrinsic muscles of the hand lying in the metacarpus deep to the palmar fascia. They arise from the tendons of flexor digitorum profundus and insert into the extensor expansions.
Step 2: Because of this arrangement, the lumbricals flex the metacarpophalangeal (MCP) joints while simultaneously extending the interphalangeal joints. Among the given single-word options, the action being tested is flexion (at the MCP joints), so the answer is flexion. This is the writing or 'upstroke' position of the hand.
Step 3: Why the others are wrong. Extension at the MCP joint is the opposite of the lumbrical action there. Adduction and abduction of the fingers are produced by the palmar and dorsal interossei respectively, not by the lumbricals.