What muscles are primarily engaged in trunk rotation and lateral bending?

The obliques play a crucial role in trunk rotation and lateral bending. This group of muscles, which includes both the internal and external obliques, is located on the sides of the abdomen. Their primary function is to assist with various movements of the torso, including twisting and bending laterally. When one oblique muscle contracts, it enables rotation of the trunk to the opposite side, while both obliques can work together to bend the torso to the side.

The rectus abdominis mainly focuses on flexing the lumbar region of the spine and does not engage significantly in rotation or lateral movements. The transverse abdominis is more involved in stabilizing the core and does not contribute directly to rotation or lateral bending. The latissimus dorsi, while it does assist with some trunk movements, primarily aids in extension, adduction, and internal rotation of the shoulder rather than directly facilitating trunk rotation or lateral flexion. Therefore, the engagement of the obliques is essential for the specified functions of trunk rotation and lateral bending.