Answer:
Extending and flexing the arm at the elbow refer to two opposite movements that occur at the joint connecting the upper arm (humerus) and the forearm (radius and ulna). Here's a breakdown of the two movements:
Flexion: Flexing the arm at the elbow involves decreasing the angle between the bones of the upper arm and the forearm. In simpler terms, it is the movement of bringing the forearm closer to the upper arm. For example, when you perform a biceps curl, you flex your arm at the elbow to lift the weight toward your shoulder.
Extension: Extending the arm at the elbow is the opposite movement, which involves increasing the angle between the bones of the upper arm and the forearm. It is the movement of straightening the arm or moving the forearm away from the upper arm. For instance, when you push a door open or perform a triceps extension exercise, you extend your arm at the elbow.
In summary, flexion decreases the angle between the upper arm and the forearm, while extension increases the angle between them.
Step-by-step explanation: