Final answer:
The seated forward bend is an example of trunk flexion, which is the anterior (forward) bending movement of the vertebral column that occurs in the sagittal plane.
Step-by-step explanation:
The seated forward bend is an example of trunk flexion. Flexion and extension are movements that occur within the sagittal plane and involve anterior or posterior movements of the body or limbs. Specifically, for the vertebral column, flexion is characterized by an anterior (forward) bending movement, which is what occurs during a seated forward bend. This movement is distinguished from extension, which involves a posterior-directed motion, such as straightening from a flexed position or bending backward. Other movements such as rotation, which is the twisting movement of the neck or body, and lateral flexion, the bending of the neck or body to the side, are not demonstrated in a seated forward bend.