 Okay, we've been talking about the rotator cuff and its six major components, supraspinatus, infraspinatus, teresminus, subscapularis, caracohumraligamate, and capsule. We've also been talking about the arches, the lateral arch underneath the acromion, the medial arch underneath the AC joint, and the subcoracoid or anterior arch, which can damage or injure the lester tuberosity, the biceps, and the subscapularis, the forgotten arch. Now I'm here to talk about the muscular tissue, the muscular tissue that dynamically helps support the stabilization of the shoulder whereas the rotator cuff is a static stabilizer. The muscles can be divided up into their individual anatomic muscles, supraspinatus, infraspinatus, teresminus, subscapularis, but also the most important distinction in evaluating muscles in the rotator cuff is whether they are volumetrically decreased and whether they have fatty infiltration. And of the two, fatty infiltration is worse because if you have fatty infiltration, it's very hard to pull that tendon and muscle over and fix it. You'll probably shred it. So many of those individuals who have severe fatty infiltration are not candidates for surgery. Now volumetrically, I will admit that that is a subjective evaluation. For instance, this supra and infraspinatus, here's the infraspinatus, should fill out this entire space. There should be only slits of fat left. So I would call this moderate to marked or at least moderate. And the amount of fatty infiltration can be compared with the trapezius to use it as a reference point. And I would say there's at least mild, perhaps mild to moderate, fatty infiltration. But I always try and make that distinction for the surgeon. Most important is when it's volumetrically severe and even more important than that when the fatty infiltration is severe. Those patients are often unsuitable for surgery.