Which muscle extends the spine?

• A. Latissimus Dorsi
• B. Spinalis
• C. Quadratus Lumborum
• D. Erector Spinae

Answer: (D)

Extending the spine is produced by the erector spinae group, a powerful back muscle system that runs along the length of the vertebral column. This group, which includes iliocostalis, longissimus, and spinalis, acts together to pull the spine into a backward bend and to help maintain an upright posture. The spinalis is one component of this group, contributing to extension, but the broader erector spinae group is the primary muscle set responsible for spinal extension.

Latissimus dorsi mainly moves the shoulder and stabilizes the trunk, not extending the spine. Quadratus lumborum stabilizes and laterally flexes the lumbar spine and can assist with minor extension, but it’s not the primary extensor.