Identifying the Upper Subscapular Nerve as a Target for Chronic Shoulder Pain

Introduction. Shoulder pain is one of the most common etiologies of chronic pain representing roughly 16% of all presenting patients (1). The branches of the subscapular nerve have been suggested as contributing to the sensory innervation of the shoulder and may have clinical value as a therapeutic target for nerve block, ablation, and stimulation. Methods. Six formalin embalmed willed body donors were used, reflecting twelve shoulders for study. Careful dissection was performed to identify the upper and lower subscapular nerves and respective branches as they approached the shoulder joint. After placing the cadaver in anatomical position, measurements were taken from two landmarks: 1) just proximal to the immediate branch from the upper subscapular nerve (USN); and 2) the medial aspect of the coracoid process (CP). The distance from the medial aspect of the CP directly to USN just proximal to its first branch was taken using a digital caliper in millimeters (table I). Results. The USN sends articular branches that directly innervate the anterior glenohumeral joint (GHJ). The average distance from the medial aspect of the CP to the USN just prior to its branches was 3.76 cm ± 0.62 cm. The average distance from the medial aspect of the CP to an intersecting perpendicular line drawn directly superior from the USN just proximal to its first branch was 0.94 cm ± 0.03 cm. Conclusions. Our findings of the USN and LSN add to prior quantitative neuroanatomical relationships of these nerves and potential targets for therapeutic intervention.