C5-T1 (cervical 5, 6, 7, 8, and thoracic 1 spinal nerves) comprise a network called the Brachial Plexus, literally meaning "arm network."
This plexus controls both sensory and motor function of the entire upper extremity (shoulder, arm, forearm, wrist, and hand).
While many would argue evolution is true, due to the fact that we "evolved from monkeys" beinf as similiar to them as we are, that is simply false. If that were true, why wouldn't the rest of the primates evolve? why would only a select few evolve and the rest stay in the current state they are in today? If evolution was possible, primates would still be evolving into humans today.
The answer is bladder
The bladder stores urine and when the brain signals to release (when we have to go pee) it releases the urine through the urethra. The answer is not kidney because it doesn’t STORE the urine it filters waste and toxins in the body into the urine to be released from the body, the actual bladder itself is the organ that stores the urine in the body.