 Okay, when you last saw me I was riding west on the humeral head trail and we were talking about near full thickness tears. Tears in pink here that went pretty deep, but maybe they didn't go all the way through or maybe they did and you weren't sure. There are a couple of tricks that you can use in this scenario. One of which is just very carefully within sections following to see if you can get fluid to drape into the tear. But if you've got a fair amount of fluid in the subacromial space, it's not a slam dunk, but the likelihood that this tear penetrates all the way through is pretty high. If you're not sure you can say pinhole sized, diminutive, full or near full thickness tear, but we are begging, urging you, prompting you to differentiate depth from antroposture length from retraction, medial, lateral or width. One other caveat I was discussing with one of my colleagues. When you have a tear with inflammation and you're really not sure just how deep it is, but it's not inconsequential, it's causing the patient symptoms, it can be very difficult to figure out depth because you're evaluating a curve structure in every plane. So look at how deep it is sagittally, coronally and even axially, which we haven't talked too much about. That's going to be our subject for our next session. But if you're unsure then that's a good time to go to what I call the 50% rule. The depth is 50% because you can't be too far off. As long as it's not full thickness, you know, if it's 70% you're only 20% off. If it's 30% you're only 20% off. And as I said it can be very hard to gauge unless you have one millimeter cuts with three dimensional reconstructions, the exact depth. And that's kind of like the term moderate. Not too bad, not too good, just in between and you can't be too far off. And you don't have any of these crimping or retraction signs to support a high grade full thickness tear. Now one other caveat as it relates to intra-substance abnormalities. When you look inside the cuff, and I'm going to blow it up for a minute, and I'm going to make the cuff pink because it's breast awareness month. When you look inside the cuff you are going to see, and I will make these little fibrils green. So you're going to see the individual fibrils in the cuff and they're going to be parallel. These are the subunits of the tendon unit. You know there's epimysium, there's perimysium, you may remember that, you may not, but that'll be a story for another day. So there's subunits within subunits. But within the major subunits you may see a few of these fibers wavy, destroyed, ill-defined, crimping, in other words doing this, and it's diffusely swollen. That is when I start jumping on the term tendon fiber failure. Which means that the cuff is degenerating, it's swollen, it's inflamed, and I am missing some of the internal anatomy. And there's often irregularity of the humeral head. So when things look very messy, like someone stirred the pot inside the cuff, you lose the internal anatomy, that's when tendon fiber failure becomes very important. Now let's go back to the sagittal projection for a moment. One of your colleagues was asking about the very far anterior fibers that go to the lesser tuberosity and go over the greater tuberosity, and those can be really challenging in the coronal projection. We'll make C for coronal. This is S for sagittal. So those tears are often over here, and you can't see them unless you have a great thin section, one or two millimeter axial, and a sagittal PD spur. They're going to be all the way in the front, and they are usually quite unpleasant and symptomatic even if they are small. Now when you get further down into the interval, you will have swelling if you have an interval injury in the adjacent soft tissue components of the rotator interval. If you get further down, then you start to get into the subscapularis, and we're going to talk about subscapularis tears and infraspinatus tears in another separate section. But remember that subscapularis tears, even when small, can be very annoying because the subscapularis attaches to the transverse ligament of the bicep, so every time you just slightly turn your arm just to right or to put your pocketbook or purse in the back seat, it is incredibly uncomfortable. So these small tears will be very symptomatic, but they are rarely operated on, in fact, almost never. But they are the cause of symptoms, so you do want to pay attention to the segments and to the interstitium of the subscapularis, and these far anterior tears may be all that's wrong, and you may only spot them in the sagittal projection interstitially. If you go to the back, remember we said nothing much happens here, like U.S. Congress, nothing much happens here in the posterior interval and in the teres. But a lot happens in the infraspinatus. We're going to dedicate a whole section to the infraspinatus, but the infraspinatus comes in curved, like the supraspinatus, but even more curved. It kind of comes in, if you can see my hands, it kind of comes in and then makes a very tight C onto the back of the humeral head and then kind of skirts underneath the supraspinatus. As a result of this curvature, you're often going to see something that looks like Bart Simpson's hair on end. It's going to look a little bit like this. I'm going to have to use a different color. I think purple may do it. Yep. There we go. You're going to see all these little hairs, except they're a lot closer together than this. I just can't draw them as close together as I need to. Maybe I'll make some more hairs. It looks a lot like Bart Simpson's hair. They're much flatter in the supraspinatus. It looks more confluent. So if you have inflammation or swelling of the infraspinatus, these hairs, which are tendon fibral subunits, spread apart. A common mistake is to call some of those hairs micro-tears. That is usually infraspinatus tendinopathy in an internal impinger. But it is extremely common in internal impingers to see partial thickness under surface tears along the deportion of the infraspinatus with pitting and pseudo cysts underneath those and a swollen infraspinatus with the hair spread apart and a little signal between them and a little bursal signal around the outside and a little bit of posterior superior labelled fraying. And that defines internal impingement and that's going to be a story for another day. So that concludes our session today. You know, we have gone from the coronal to the sagittal to talking about length and width and depth to naming some important tears to giving you some caveats to get out of jail when you have a tough situation. And in our next sessions we're going to focus on the subscapularis, the infraspinatus and the axial projection and its contribution to rotator cuff assessment and then we're going to dive into some cases. Thanks.