Divides the body into left and right halves.
The actions of flexion and extension occur along this plane (forward and backward movement or up and down movement). An example would be lifting and lowering your leg. The leg is moving in the sagittal plane.
The 'frontal' plane divides the body into front and back portions. The terms 'anterior' and 'posterior' relate to the frontal plane; the actions of abduction and adduction happen along this plane. An example would be taking your arm out to the side and bringing it back. The arm is moving in the frontal plane.
The 'transverse' plane divides the body into upper and lower parts, i.e., it cuts us into top and bottom parts. The terms 'superior' and 'inferior' refer to the transverse plane; rotation happens within this plane. When you twist at your waist, you are rotating in the transverse plane. For example, if your arms are parallel to the floor, you perform horizontal shoulder flexion when you bring your arms together in front of your chest.