 Okay, let's talk a little bit about the the rotator cuff and As you know, this is Our deep foray into the jungle of the shoulder. It's like shark week. It's it's shoulder week We've got the humeral head and neck and then we've got pretend where anterior we've got the supraspinatus muscle and Then that transitions into the myotendinous junction which is of variable thickness And a variable length And that junction can be divided up into a thicker Area where the tendon fibrils actually have a greater diameter and that's known as the the cable portion of the cuff And then we have kind of the arc shape and I really should make it Really should make it thinner because they are thinner. We have the arc shaped Crescent portion of the cuff And then we finally tamp down the cuff As the footprint or foot plate. That's the attachment portion That goes on the marginal edge of the humerus greater tuberosity. So we've got muscle Myotendinous junction cable portion Crescent portion of the myotendinous junction Footprint but still tendon so there's a pretty long tendinous area And some individuals like to describe injuries to the cuff As being that which has occurred either in the cable or in the crescent or as a tear that is Crescent dominant configuration or cable dominant configuration And that's going to be a story for a little bit later because that's a little more advanced and a little more complex But when somebody has a real long cable Thicker portion of the myotendinous unit They're going to tear and retract a little bit differently Then if they have a longer crescent portion of the cuff Then there are other descriptors that involve the medial lateral orientation of the cuff and a lot of these Basic tenets for the supraspinatus Will apply for the infraspinatus And the teres although the teres almost never tears And it'll apply for the subscapularis although The shape of the subscapularis Belies a slightly different set of descriptors So we'll get in we'll get into the subscapularis on its own. Let's pretend We're talking supra and in front together right now So then we're going to look at in the coronal plane whether we have a footprint tear a crescent tear a cable tear Or we may even ignore these if we can't distinguish them and just say the tear is medial to the foot Plate or footprint or it's at the myotendinous junction, which would be here or it's in the muscle Or there could be even a cyst that's located in the muscle called the sentinel cyst from a very small tear Which will be a story. We'll also tell a little bit later Well, then look at Where the cuff has retracted to if it ruptures and breaks into two parts Then we may describe this medial lateral rupture As having a retraction dimension of x Or we might say That the retraction Lies just underneath the ac joint As long as we communicate That's fine Is it preferable to say it lies under the ac joint where the retraction dimension of four and a half centimeters? Yeah, it is that's simple direct better communication But one or the other will usually suffice if you haven't had your second cup of coffee yet Another way to describe and an important way to describe Cuff injuries is by their location relative to the humerus Now we've already said that this portion of the cuff that sits right on top of the humerus and attaches to it Is called the foot plate or footprint If we look from the top down, you will see That the supraspinatus comes over from medial to lateral And goes on the humeral head and curves And all the fibers will curve And if you internally rotate the shoulder, they will curve even more And the more they curve the harder they are to evaluate That's why we don't want to internally rotate the shoulder And the more they curve the more magic angle effect You're going to get making diagnosis a little bit tougher So we like to have the hand either neutral or slightly externally rotated The infraspinatus, which we're going to attack in a few moments And we're going to change color for the infraspinatus for a moment. Hope we don't run out of colors Will come right underneath the supraspinatus and they interdigitate with each other So the infraspinatus is creeping right underneath the supraspinatus It actually goes pretty far forward But in the sagittal you'll see a space between the two right here And I'll draw the sagittal for you known as the posterior rotator interval Which means there's an anterior rotator interval And there's also a far posterior rotator interval So some people refer to this as the central interval But as you get further out, you're going to have a very difficult time distinguishing the fibers of the infra and suprab because they interdigitate Another interesting aspect of rotator cuff anatomy Is as the supraspinatus comes forward, it may send some fibers over to the lesser tuberosity Let's pretend we have a humerus underneath there. I'll make my humerus blue again just to be consistent And there is my lesser tuberosity And here are my lesser here are my fibers going over just a few go over to the lesser tuberosity from the supraspinatus And that's only in the last 10 years been recognized And only in the last 10 or 20 years has the degree of interdigitation between these two structures been recognized The supraspinatus tears more frequently than the infraspinatus often as a result of contact abnormalities When the arm is over the head Especially when it's in front of the mid coronal plane So when it's in front of your mid body Or the mid scapular line That's where the supraspinatus gets the most forces applied to it Whereas the infraspinatus has more forces applied to it when you're in the cocking motion When the arm and elbow are behind that mid coronal line along the scapular line or mid scapular line So now let's go back to our discussion We got a little bit sidetracked regarding the humeral head. We said the foot plate or footprint is a rather complex structure and when you have a tear say in this location, it is not Let me repeat it is not an articular sided tear Stop doing that There's no articular surface there. There's no synovium there. There's no cartilage there It's on the humeral head surface of the foot plate or footprint and it is concealed It's invisible They can't get in there from this direction and see it They can't get in there from the deltoid approach and see it It's hidden inside these fibers and is usually a nonsurgical tear if it gets inside the humeral head And pits the humeral head. It's got a rim rent component These are often referred to as concealed interstitial delamination tears of the foot plate or footprint with rim rent penetration Then if we get a little further over Where in the region of the bare area Now a little bit of fluid likes to collect here So you're always going to see a little signal there because there's no cartilage That's why it's called the bare area and the cartilage starts right about here Now we have highland cartilage. So if you have a tear here you'd say it's a bare area tear Right next to the foot plate or footprint if you have a tear underneath here You would say that it's an articular sided tear So let's stop right there let's stop right there and Pause for a minute and then we're going to come back to this same diagram And we're going to drill into the next layer of intelligentsia Be back in a minute