The neck and upper back are often the source of arm pain. The nerves that supply the arm come from the brachial plexus, which arises in the lower half of the neck.
Also, the muscles, nerves, ligaments and tendons of the arm can all, potentially be the cause of arm and hand pain.
Well-known conditions that affect the arm are Tennis Elbow, Carpal Tunnel and Repetitive Strain Injuries.
An example of arm pain:
When the lower neck is dysfunctional, the nerves that supply the triceps muscle become over active and cause this muscle to tighten and develop Trigger Points.
This causes a general arm ache, with the elbow and shoulder in particular becoming painful.
Treatment in this instance would best be spinal manipulation for the neck, and acupuncture for the triceps muscle.
There are other treatments that are equally good, such as massage and cranio sacral therapy, for people who find the thought of manipulation & acupuncture too daunting.
There are many possible causes of arm pain, the majority respond favourably to osteopathic treatment.