Which plane is associated with the actions of flexion and extension?

The sagittal plane is the one associated with the actions of flexion and extension. It divides the body into right and left halves, allowing movement to occur forward and backward. Flexion involves decreasing the angle between two body parts, such as bending at the elbow or knee, while extension increases the angle, such as straightening the arm or leg. These actions occur in the sagittal plane because they involve movements that bring parts of the body closer together (flexion) or further apart (extension) along the anterior-posterior axis.

In contrast, the coronal plane handles movements that take place side to side, such as abduction and adduction, while the transverse plane pertains to rotational movements around the vertical axis. The oblique plane allows for diagonal movements, which do not strictly fall under flexion or extension actions. Understanding the relationship between the sagittal plane and flexion/extension is key to analyzing human movement in clinical biomechanics.