What are the causes of left arm pain radiating down to hand?

Cervical nerve pinch: Pinch nerve in neck C6 goes to thumbc7goes to middle fingers MRI of neck and confirm with selective netve root block easily fixed when found.

Several: This can be caused most typically from a neck or a shoulder problem . If if occurs from the elbow down it could be related to a neck or elbow issue. If really depends on where the pain starts and where it radiates and what makes it feel worse or better and what associated symptoms that may be present. You should see your doctor to make sure this is not a heart or lung issue that can cause this.