Which muscle group abducts the 2nd, 3rd, and 4th digits at the MCP joints?

Which muscle group abducts the 2nd, 3rd, and 4th digits at the MCP joints?

• A. Dorsal interossei
• B. Palmar interossei
• C. Lumbricals
• D. Flexor digitorum profundus

Answer: (A)

Abduction at the MCP joints of the index, middle, and ring fingers is carried out by the dorsal interossei. These muscles lie between the metacarpals and insert on the proximal phalanges and extensor expansions of the digits. Their action is to move the fingers away from the middle finger, so digits 2, 3, and 4 are drawn laterally or medially relative to the hand’s axis, with the 3rd digit serving as the reference point. In contrast, the palmar interossei pull digits toward the middle finger (adduction) at the MCP joints, the lumbricals primarily flex the MCP joints while extending the IP joints, and the flexor digitorum profundus flexes the distal joints rather than producing abduction at the MCPs.

Abduction at the MCP joints of the index, middle, and ring fingers is carried out by the dorsal interossei. These muscles lie between the metacarpals and insert on the proximal phalanges and extensor expansions of the digits. Their action is to move the fingers away from the middle finger, so digits 2, 3, and 4 are drawn laterally or medially relative to the hand’s axis, with the 3rd digit serving as the reference point. In contrast, the palmar interossei pull digits toward the middle finger (adduction) at the MCP joints, the lumbricals primarily flex the MCP joints while extending the IP joints, and the flexor digitorum profundus flexes the distal joints rather than producing abduction at the MCPs.