Final answer:
Nodding your head up and down is an example of flexion and extension, which are types of angular movements where the angle between bones changes.
Step-by-step explanation:
Nodding your head up and down is an example of flexion and extension. This type of movement belongs to angular movements, which are produced when the angle between the bones of a joint changes. Specifically, flexion, or bending, refers to decreasing the angle between bones, which is the action when nodding the head downward. Conversely, extension refers to increasing the angle between bones, which occurs when lifting the head back up to the neutral position. These movements take place in the sagittal plane and can be seen at several joints, including the shoulder and knee, in addition to the neck.