Which muscle extends the spine?

• A. Rectus Abdominis
• B. Latissimus Dorsi
• C. Erector Spinae
• D. Gluteus Maximus

Answer: (C)

Extending the spine is done mainly by the erector spinae, a group of muscles that run along each side of the vertebral column. When they contract together, they straighten the trunk from a bent position and help you stand up tall, support good posture, and control back extension during movements like back arches or lifting with a straight back. The rectus abdominis, by contrast, flexes the spine, bringing the chest toward the pelvis. The latissimus dorsi is primarily a shoulder muscle, moving the arm, and while it can influence trunk mechanics indirectly, it doesn’t actively extend the spine. The gluteus maximus mainly extends the hip and stabilizes the pelvis, not the spine.