Triangular interval syndrome: A differential diagnosis for upper extremity radicular pain.

This case report describes a 57-year-old female who experienced symptoms of scapular pain with pain radiating into the right upper extremity. Initial medical referral suggested, nerve entrapment of a cervical origin. However, the patient did not fit the clinical prediction rule for cervical radiculopathy. Radial nerve bias was positive without cervical provocation, with symptom reproduction at the lateral scapular area. Treatment addressed mechanical dysfunction at the triangular interval formed by the teres major and triceps, comprising manual therapy, neural mobilization, corrective exercise and pain modalities. Reduction in symptoms was observed with a decrease in right scapular and arm pain and improved radial nerve mobility. The triangular interval is described as a predominant contributor to the symptomatology secondary to entrapment and adverse neural tension of the radial nerve. The anatomical and physiological basis is enumerated.