 So welcome back to our discussion. This is shoulder week also known as shark shoulder week kind of like shark week We're drilling into the shoulder and we're going to drill further earlier on we were talking about the locations medial laterally of Rotator cuff injuries. We began with Foot plate or footprint injuries that may or may not penetrate bones so-called rim rent configuration tears that are concealed or hidden either word is fine And when they're somewhat linear and small we refer to them as CIDs concealed interstitial delaminations with or without rim rent component Then if you have involvement of the rotator cuff Right over top of this yellow area say right here Say there's a small under surface tear along the bare area of the interarticular space A partial thickness tear as long as it doesn't communicate, but we're not into a discussion of death just yet Then if you have a tear over here, it would be in the articular surface Or the articular surface region of the humeral head either the lateral articular surface the apex or the medial portion But you're also going to describe the tear not only by its relationship to the humeral head Who's anatomy now you know in excruciating detail But also by its relationship to the muscle the myotendinous junction the cable the crescent and the foot plate or footprint So that takes us to our next discussion Of the supraspinatus and secondarily we can extrapolate it to the infraspinatus that takes us to the sagittal projection So we believe it or not. We're still on the basic discussion Of rotator cuffs. We haven't gotten to all the crazy names and all the other Crazy stuff we're going to cover and I made my sagittal humeral head really big It's because I'm not a great drawer And we'll call this a anterior and this p Posterior my p isn't very good. I better make my line a little bit thinner And now let's get our Let's get our rotator cuff going here in purple Here's the supraspinatus portion of the cuff And then the supraspinatus portion of the cuff Is connected to the infraspinatus portion of the cuff Righted about just past the apex of the humeral head is about usually where they transition We'll make our infraspinatus slow green Here's our infraspinatus and this area here which is connected by a small Fibroelastic membrane which can be very short Can be congenitally longer or it can acquired Stretch out So it can become longer from front to back over time when you tear Either one of these You're going to look at depth which we're going to discuss in a few minutes But right now I want to concentrate on the concept of length When you're looking at depth and length this concept really resonates more when you're dealing with flat tendons So depth is obvious it's going to be this length is a to p in the shoulder So if you tore this entire structure from front to back and you had nothing here you would say there's a complete And if it goes all the way through full thickness and then you use the coronal to describe the retraction If it's just the anterior half then you'd say anterior supraspinatus and you'd give them the length So the length might be something like this if the tear is this long from here to here If you're missing the whole supraspinatus you'd say it's complete And it has x length If it goes into the infraspinatus you'd say it's got the anterior fibers of the infraspinatus All the fibers of the supraspinatus and now it's four centimeters a to p We'll talk about depth in a moment We're talking simply about completeness And then if it goes all the way around back, it's got the entire infraspinatus The entire supraspinatus. It's a complete infraspinatus. It's a complete supraspinatus We'll say it's a full thickness Tear the entire thickness of both tendons and the length is five centimeters and the humeral head is now bald And we use that term bald humeral head This little spot right here This fibroelastic membrane and light blue Maybe we need another color like red In red We say it can be a little bit longer. It can stretch out. You can be born with a longer one But this area is prone to Microtrauma micro separation and because it's very thin and membranous diffusion So if you're going to get some diffusion Of synovial fluid and fluid Into The rotator cuff muscles. It's often going to come from right here And it'll come out of here as a little tiny thing that you can hardly even see or you cannot see Because it's a diffusion event And then it'll go into the muscle and it'll balloon As it tracks from medial to lateral And that's known as a cystic tear And as they balloon if they trumpet from medial to lateral Let's say it comes out and it gets in the muscle and it does something like this It's called a sentinel cystic tear. In other words, it has a little blowhole at the very end The little hole where it comes out of is very difficult to see sometimes you see it Sometimes you don't Very rarely will something like this be a true ganglion that arises from the tendon in the muscle but has no communication with the joint 90 percent of the time it came from the joint from a small rotator cuff or rotator interval injury And we said there are other intervals There's an anterior interval right here That's the space between the supra And the subscapularis which we will make now In blue we'll make it a lot thicker Here's our subscapularis And the subscapularis unlike these other tendons That fan out and flatten out and blend together and make a mesh Of low signal intensity almost like a net The subscapularis doesn't do that The subscapularis usually has four or five dominant tendons inside it Which you can see that divides it up into various segments So you don't have to say which segment it is you just should probably say upper third upper fourth You know middle third You know second fourth whatever just be descriptive the the clinician really only cares about generalities here The upper half of it is ruptured the lower half of it is ruptured. It's a partial thickness there It's an interstitial tear. It's a concealed tear We're going to get to that as a separate subject when we get into subscapularis tears But that's an introduction to it and one of the best sequences to diagnose subscap tears is the sagittal projection Because you're absolutely perpendicular to this structure and it's a rather complex structure as we'll see in a few moments We also have another interval That other interval is The deep posterior interval between the infraspinatus And the teres minor We'll make the teres minor some pretty color like orange Now the good news Here is it's a little like politics and us congress. Nothing ever really happens here So you don't have to be you don't have to be too concerned about it Nothing ever really happens in the In the teres and not much happens here except one thing This is a good place to stick your needle when you're doing An arthrogram or an mr. Arthrogram. It's very safe. It's easy to get into. There's no important structures here That are a biblical or political significance So you can get in here without a lot of worry and if you miss the consequences Are usually non-existent or nominal This is also a great projection to assess where your pits or pseudosists are And you know, they look somewhat like this either irregularity or you actually see subconvial or subcortical cysts and they tell you Kind of what's going on physiologically and patho anatomically with the shoulders So if a lot of these changes are in the front, let's pick another color like pink If a lot of these cystic changes are in the front You know that there's going to be contact of the humeral head With the subacromial arch and the acromion when the patient's arm is forward and over the head Kind of anterior. This is called external impingement Whereas if most of the pits and irregularities and pseudosists Are in the back near the infraspindatus. Remember, this is posterior. Here's our p Then most of the contact is going to occur in the cocking position This is called internal impingement And there's another one if a lot of these pits and irregularities are deep to the subscap Then there's a pretty good chance you're dealing with subcoracoid far anterior arch impingement Which is the least common of the three And there's another one called enteros superior impingement, which is a story for another day So i'm going to stop right now regarding the sagittal projection You know, that is my story for the sagittal projection It's the introductory story, but yet It's pretty complex because the shoulder Is a ball and socket joint. It's pretty complex and ball and socket joints are the toughest ones to assess Let's take a breather. You take a breath and then we'll come back and we'll continue on with our diagrams