Conditions of the head, neck, thorax, and shoulder may occur simultaneously with arm pathology or produce symptoms perceived by the patient to originate in the elbow, wrist, or hand. Identification of the tissue disorder and associated impairments, followed by matching the rehabilitative intervention to address these issues, leads to optimal outcomes. With this goal in mind, the hand therapist needs to recognize clinical findings that signal potentially serious medical conditions of the brain, cervical region, chest, or shoulder. Additionally, less serious but potentially debilitating, musculoskeletal or neurogenic pain from proximal sources must also be differentiated from somatic pain originating in the elbow, wrist, or hand so that the clinician can decide to further examine and intervene or refer to an appropriate health care provider. This article describes clinical findings that suggest the presence of serious medical pathology in the head, neck, or thorax and presents a screening algorithm to assist in discriminating pain derived from local structures in the distal arm from referred pain originating in the more proximal regions of the shoulder, thorax, neck, or brain.