Dorsal interossei action?

Dorsal interossei action?

• A. Abduct digits 2,3,4
• B. Adduct digits 2,4,5
• C. Abduct digits 1,2
• D. Flex MCP joints

Answer: (A)

Dorsal interossei abduct digits away from the middle finger. These four muscles lie between adjacent metacarpals and insert on the sides of the proximal phalanges with extensor expansions, so their contraction pulls the fingers laterally, away from the line through the third digit. In practice, they abduct digits 2, 3, and 4 and also assist in flexing the metacarpophalangeal joints while extending the interphalangeal joints. This explains why abducting digits 2–4 is the correct action. By contrast, palmar interossei adduct digits toward the middle finger (toward the third digit), which is the opposite motion, and other options describe functions not primarily attributed to the dorsal interossei.

Dorsal interossei abduct digits away from the middle finger. These four muscles lie between adjacent metacarpals and insert on the sides of the proximal phalanges with extensor expansions, so their contraction pulls the fingers laterally, away from the line through the third digit. In practice, they abduct digits 2, 3, and 4 and also assist in flexing the metacarpophalangeal joints while extending the interphalangeal joints. This explains why abducting digits 2–4 is the correct action. By contrast, palmar interossei adduct digits toward the middle finger (toward the third digit), which is the opposite motion, and other options describe functions not primarily attributed to the dorsal interossei.