Here is a description of the nerves that affect the forearm and hand: Three independent nerves supply the cutaneous innervation of the hand. From lateral to medial, these nerves include the superficial branch of the radial nerve, the median nerve, and the ulnar nerve. These peripheral nerves originate from the C5 to T1 levels of the spinal column. The sensory distribution discussed here includes both the ventral and dorsal aspects of the hand ending proximally at the level of the wrist. Also briefly discussed here will be a set of muscles innervated by these nerves as they supply the cutaneous innervation of the hand.

C5 refers to cervical 5, so that would be originating in the lower neck, and T1 is actually a junction of C-7 and T-1 (thoracic 1), and lots is going on there if the C-8 nerve gets compressed. This is common in scoliosis. If the C8 nerve is compressed or irritated, additional symptoms may occur, such as:Pain in parts of the shoulder, forearm, hand, and/or little finger.Numbness in the forearm and/or handWeakness in the wrist, hand, and/or fingers.

(cited from several medical papers)

Can you tell I'm an anatomy geek?