Fig. 3.

Tangent lines used to evaluate for muscle atrophy. Tangent lines can be used to evaluate muscle atrophy in the setting of a rotator cuff tear. Lines are drawn between the coracoid tip and scapular spine (supraspinatus), the coracoid and the scapular tip (subscapularis), and scapular spine and scapular tip (infraspinatus and teres minor) on sagittal oblique images. A positive tangent sign is present when the respective muscle bellies do not cross their tangent line. “Used with permission of Mayo Foundation for Medical Education and Research. All rights reserved”