Anatomical movements describe the motion of bones and muscles in reference to the standard anatomical position. These motions often pair with a complementary movement in the opposite direction. Many movements travel along the frontal, sagittal, or transverse anatomical planes. Frontal plane movements occur toward or away from the body's midline, such as raising the arms to shoulder level laterally and bringing the arms back down to the side of the body. The sagittal plane movements travel between a person's anterior and posterior sides, such as moving the arm forward and backward during walking. The transverse plane movements include rotating and twisting, such as turning the head from side to side.