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 what people often flex to show off their muscles. The biceps is responsible for the flexion of the elbow joint, or in simpler terms, bending the arm. It also plays a role in supination, which is the action of turning the palm up or forward.

2. Triceps: The triceps brachii is a three-headed muscle located at the back of the arm. Its primary function is the extension of the elbow, or straightening the arm.

These muscles work together to allow the arm to move and function. When you want to bend your arm, your biceps contract (shorten) and your triceps relax (lengthen). When you want to straighten your arm, your triceps contract and your biceps relax.

These muscles are attached to the bones of the arm (the humerus, radius, and ulna) via tendons. The contraction of the muscles pulls on these tendons, which in turn moves the bones.

In summary, the biceps and triceps work in a sort of "tug of war" to allow the arm to bend and straighten. This is a great example of a pair of muscles working in what's called an antagonistic pair - where one muscle relaxes while the other contracts.