Which muscles are primarily responsible for lateral spinal flexion?

Lateral spinal flexion is primarily facilitated by the oblique muscles and the quadratus lumborum. The obliques, consisting of the external and internal oblique muscles, play a crucial role in flexing the spine sideways. They help in bending the torso to the side as well as rotating it. Their positioning and orientation enable them to engage effectively during lateral flexion movements.

The quadratus lumborum, located in the lower back, also contributes significantly to this motion. It assists in stabilizing the pelvis and lower spine and directly aids in side-bending. Because of their anatomical functions, the combination of these two muscle groups effectively supports lateral flexion of the spine, making them primarily responsible for such movements.