Pain originating from an intrinsic shoulder problem typically stays below the deltoid muscle and rarely extends below the elbow, whereas pain radiating below the elbow suggests a neck origin.

“the intrinsic shoulder problem such as a rotator cuff tear or inflammation bursitis Etc usually travels down underneath the the pain underneath the delt the big deltoid muscle but almost never goes below the elbow so if I see pain that's in the shoulder going below the elbow I'm thinking maybe neck or maybe something else”