Final answer:
The obliques assist in both trunk rotation and lateral flexion. These muscles play a crucial role in posture, movement, and protecting internal organs by contracting in response to brain signals to maintain balance and prevent fatigue during various activities.
Step-by-step explanation:
In addition to trunk rotation, the obliques are also responsible for trunk flexion and lateral flexion. The obliques, which include the external and internal obliques, are part of a group of abdominal muscles that are essential for maintaining posture, moving the trunk, and protecting internal organs.
They are also key contributors to maintaining an upright posture and ensuring the stable positioning of the vertebral column during different physical activities. Because of the alternate contraction and relaxation directed by the brain, these muscle groups prevent fatigue and support the body's balance and movement. For example, when carrying a heavy load on one shoulder, the oblique muscles on the opposite side contract to help maintain an upright posture and balance the load, demonstrating both trunk rotation and lateral flexion.