Question

what is the long narrow muscle runs from the elbiw to the wrist

Answer 1

palmaris loungus muscle.
I think so it is correct!!!

Answer 2

The triceps brachii, as its name indicates, has three heads whose origins are on the scapula and humerus. These three heads merge to insert on the olecranon of the ulna. Most of the muscles that move the wrist, hand, and fingers are located in the forearm.