What were the two muscles that you saw in the arm anatomy in the gizmo? Explain how they work together with the bones of the arms?

The two main muscles you typically see in arm anatomy are the biceps and the triceps.

1. Biceps: The biceps brachii is a two-headed muscle located on the front of the arm, and it's the muscle most people flex in order to show off their arm strength. The biceps is responsible for the flexion of the elbow joint, or in simpler terms, bending the arm. It also helps to turn the hand to face palm uppermost, a movement called supination.

2. Triceps: The triceps brachii is a three-headed muscle located at the back of the arm. It is responsible for the extension of the elbow joint, or straightening the arm.

The biceps and triceps work together to enable the arm to move and function. When you want to bend your arm, the biceps muscle contracts (shortens), and the triceps muscle relaxes (lengthens). When you want to straighten your arm, the opposite happens - the triceps contracts and the biceps relaxes.

These muscles work in conjunction with the bones of the arm - the humerus (upper arm bone), and the radius and ulna (lower arm bones). The biceps is attached to the radius and helps to stabilize the upper arm while the triceps is attached to the ulna and helps to stabilize the lower arm. The muscles pull on these bones to produce movement.