What movements happen at this joint?
Lateral flexion happens at the trunk when you pull your shoulder toward the side of your thigh, decreasing the angle between your shoulder and your thigh.
What muscles make these movements happen?
The muscles that laterally flex your trunk are the same as those that flex it forward, just in different combinations. If you contract the right side of your rectus abdominis and your right external and internal obliques, then you flex to the right. If you contract the left side of your rectus abdominis and your left external and internal obliques, then you flex to the left.
What exercises make these muscles work?
Same basic exercises, same basic advice to exercise your range of motion in all directions. Teapots and windmills specifically involve lateral flexion.
