Final answer:
The median nerve is the main systemic nerve extending down the mid-forearm to the hand, situated between the ulnar and radial nerves, and is essential for controlling hand and finger movements.
Step-by-step explanation:
The primary nerve of the arm that extends down the mid-forearm to the hand is the median nerve. This systemic nerve is important for the movement and sensation in the hand and forearm, located between the ulnar and radial nerves.
The median nerve passes through the carpal tunnel and innervates muscles such as the flexor digitorum superficialis and flexor digitorum profundus, which are situated in the anterior compartment of the forearm and facilitate finger flexion and hand movements.
As people engage in activities like typing or playing a musical instrument, the median nerve, along with these muscles, plays a crucial role. If these muscles or the nerve become irritated, it could lead to conditions such as Carpal Tunnel Syndrome.