Which joints are primarily involved in forming a composite fist?

Which joints are primarily involved in forming a composite fist?

• A. Metacarpophalangeal joints and proximal interphalangeal joints
• B. Carpometacarpal joints and distal interphalangeal joints
• C. Elbow and shoulder joints
• D. Metatarsophalangeal joints and DIP joints

Answer: (A)

Forming a composite fist mainly depends on bending the fingers at the metacarpophalangeal joints and the proximal interphalangeal joints. When you curl your fingers, the flexor muscles pull at the knuckles (MCP joints) and at the middle joints (PIP joints), drawing the fingers toward the palm and bringing the fingertips into contact with the palm. The distal interphalangeal joints also flex as part of the motion, but they’re not the primary drivers of the fist’s compact shape—MCP and PIP flexion create the bulk of the curl. The other options involve joints that aren’t the main flexion points for forming a fist (the carpometacarpal joints aren’t the primary finger-bending joints, and the elbow/shoulder are upstream joints; and the presumed toe joints are unrelated to the hand).

Forming a composite fist mainly depends on bending the fingers at the metacarpophalangeal joints and the proximal interphalangeal joints. When you curl your fingers, the flexor muscles pull at the knuckles (MCP joints) and at the middle joints (PIP joints), drawing the fingers toward the palm and bringing the fingertips into contact with the palm. The distal interphalangeal joints also flex as part of the motion, but they’re not the primary drivers of the fist’s compact shape—MCP and PIP flexion create the bulk of the curl. The other options involve joints that aren’t the main flexion points for forming a fist (the carpometacarpal joints aren’t the primary finger-bending joints, and the elbow/shoulder are upstream joints; and the presumed toe joints are unrelated to the hand).