Superficial Nerves of the Arm and Hand (Posterior View)

[Continued from above] . . . Some of these impulses are sent from various parts of the brain and spinal cord; some come from sense organs located in the joints, ligaments, and tendons; and some come from the muscles themselves. Typical among these peripheral nerve branches in this section of the nervous system are the ulnar nerves - which are branches stemming from the cervical nerves - that supply impulses to and from the muscles of the forearms and hands and from the skin of the hands.

As major sensory components of the body, the hands are the destination for a majority of the nerves in this part of the nervous system. They house a myriad of sensory nerve endings to detect pressure and temperature through the skin cells of the palm. Even the hand muscles, which perform very delicate and precise movements, are driven by about 200,000 neurons.

All of which allows the peripheral nerves in the arms and hands to collect information about the external conditions in relation to the body's internal state, to analyze this information, and to initiate appropriate responses to satisfy certain needs. The speed at which we can, for instance, remove our hand from a surprisingly hot surface exemplifies the power of the central and peripheral nervous systems in coordination within the upper extremities. Remarkably, the nervous system transmits such messages to the brain at speeds of 180 miles per hour!