Ace the 94A Kinesiology Challenge 2026 – Flex Your Knowledge Muscles!

Flexing the vertebral column is accomplished mainly by the muscles of the anterior abdominal wall, especially the rectus abdominis. This vertical, strap‑like muscle runs along the front of the abdomen from the pubic region up to the lower ribs. When both sides contract, the rectus abdominis pulls the rib cage toward the pelvis, bending the spine forward and bringing the upper body toward the lower body. The external oblique also contributes to trunk flexion, but its primary roles are lateral bending and rotation when it acts on one side. The other two muscles listed don’t primarily flex the spine: a back muscle that mainly moves the arm and assists in other movements, and a shoulder/neck muscle that elevates the scapula, neither of which directly flexes the vertebral column. So the rectus abdominis is the best fit for flexing the vertebral column.