Which term describes any movement that increases (opens) the angle at a joint, such as extending the knee, hip, and ankle?

Which term describes any movement that increases (opens) the angle at a joint, such as extending the knee, hip, and ankle?

• A. Flexion
• B. Abduction
• C. Extension
• D. Adduction

Answer: (C)

Extending a joint means straightening it to increase the angle between the two bones. When you straighten the knee, hip, or ankle, you’re opening up that angle, which is extension. Flexion, by contrast, bends a joint and decreases the angle. Abduction moves a limb away from the body's midline, and adduction moves it toward the midline, which are directional terms rather than changes in joint angle. So the movement described—opening the joint angle by extending these joints—fits extension.

Extending a joint means straightening it to increase the angle between the two bones. When you straighten the knee, hip, or ankle, you’re opening up that angle, which is extension. Flexion, by contrast, bends a joint and decreases the angle. Abduction moves a limb away from the body's midline, and adduction moves it toward the midline, which are directional terms rather than changes in joint angle. So the movement described—opening the joint angle by extending these joints—fits extension.