What action involves flexion and extension?

Flexion and extension are movements that occur in a sagittal plane around a mediolateral axis. Flexion generally refers to the decrease in the angle between two body parts, while extension is the increase in the angle. Hyperextension is a specific type of extension that occurs beyond the normal range of motion, effectively extending a joint beyond its typical straightened position.

In this context, hyperextension involves moving a joint such as the knee or elbow in a way that goes beyond the neutral position. For instance, when extending the neck backwards beyond the upright posture or when extending the arm straight back behind the body, this movement qualifies as hyperextension.

Other choices involve different types of movements that do not inherently include both flexion and extension. Rotation refers to turning around an axis, adduction involves movement toward the midline, and dorsiflexion pertains specifically to flexing the ankle joint, raising the toes upward towards the shin.

Thus, hyperextension stands out as it explicitly deals with actions involving the increase of joint angles beyond the standard anatomical position, therefore encompassing the essence of both extension and the specificity of hyperextension.