Which muscle group is located in the lower back?

The erector spinae is the muscle group that is primarily located in the lower back. This group is composed of three columns of muscle, known as the iliocostalis, longissimus, and spinalis. The erector spinae plays a crucial role in maintaining posture, extending the spine, and facilitating movements such as bending and twisting the torso. These muscles run vertically along the spine, helping to support and stabilize the vertebral column during various activities.

While the quadratus lumborum is also a muscle found in the lower back, it primarily acts to provide stability and support rather than functioning as a major extensor like the erector spinae. The latissimus dorsi, on the other hand, is positioned more toward the sides and back of the torso rather than strictly in the lower back region. Finally, the rectus abdominis is located in the front of the abdomen and is primarily involved in flexing the spine and providing abdominal support. Thus, the erector spinae stands out as the primary muscle group a student should identify when considering the lower back.