hello everybody and welcome back to another anatomy video today we have a good one we're going to be looking at the anatomy of the shoulder in some detail on an mri scan now you might be wondering why i have an x-ray up if we're going to be looking at an mri scan and i just want to make sure that we're all on the same page i feel like with mri a single slice people often get confused because their understanding of the surrounding anatomy is poor and i want to just cover some of those anatomical structures here on an x-ray first now the great thing about an x-ray is you can see the joint in its entirety you're not just looking at a single slice and we can see all the structures from anterior to posterior overlaid over each other now the way we're going to approach each mri is by firstly looking at the bones then looking at the ligaments moving on to the capsule and the labrum of the glenohumeral joint and lastly looking at the rotator cuff muscles that's around the shoulder so let's identify those structures here and make sure we know how they relate to one another before heading on to an mri scan so we'll start with the bones we can see we should all know that the clavicle comes across here and attaches by the ac joint to the acromion here so we have our chromium of our scapula here anteriorly coming forward is our coracoid process this is a really important landmark when we're looking at mri scans we can see our shallow glenoid fossa of our glenoid here and we can see the scapula posteriorly here behind the lung fields all the way up the spine of our scapula coming across to our acromion there we can see our humerus here with our humeral head that's going to articulate with this glenoid photo this is our glenohumeral joint that we're going to be covering here you can see how those bones relate to one another and the most important thing here to remember is the coracoid process is coming out anteriorly and our chromium is posteriorly and when we're in an mri we can use those landmarks to try and figure out our orientation of our mri slice then let's have a look at some of the ligaments we've got our coracoclavicular ligaments coming up here attaching the coracoid to the clavicle distal clavicle we've mentioned our ac our acromioclavicular joint here and we've got a really important coracoacromial ligament that comes across here and makes the roof of our coracoacromial arch that we'll cover later in mris we also have some ligaments that stabilize the joint itself we've got our superior our middle and our inferior glenohumeral ligaments now you can see i've drawn that inferior glenohumeral ligament with a long looping segment like that and that's because when we lift our humerus we need space for that ligament to then stretch over and the whole shoulder is a balance between finding stability in the joint you can see it's a really shallow joint and it takes quite a lot to keep that humerus in place so we really need good stability if you think we used to need to hang from branches have a whole body weight coming through a single joint but we need the mobility as well we need to be able to move our arms in multiple different planes and the whole shoulder joint is just that trade-off between getting maximum mobility in the shoulder but still having enough stability to maintain the integrity of that shoulder joint so the last thing we're going to look at are the muscles surrounding the shoulder and you may know these as the rotator cuff muscles so firstly we have our supraspinatus above the spine of the scapula coming here above the spine it's going to go over our coracoid underneath our acromion and attach here to the superior border of the greater tuberosity then anterior to the scapula between the scapula and these ribs we have our subscapularis that's going to come through here it's going to come anterior to the humerus itself and attach to our lesser tuberosity here then posteriorly under the spine our infraspinatus posteriorly is going to come round the the humeral head here and attach this middle portion of our greater tuberosity and slightly inferior to that we have our teres minor also coming around the humor head posteriorly attaching to the inferior border here of our greater tuberosity of the humerus so we have our greater tuberosity that has our supraspinatus infraspinatus and our teres minor attaching and we have our lesser tuberosity here with our subscapularis tendon coming all the way to it in between here is our intertubercular groove we have our or our bicipital group we have our long head of bicep tendon running through this groove over the top and attaching to the bicep anchor on top of our labrum here our superior labrum here now this is the only tendon in the body that is actually intracapsular that tendon runs through the capsule of our glenohumeral joint a long header bicep goes there so where does our short head go when our short head comes up to our coracoid process there now you can see with these lines here i mean this looks like a picasso drawing there's so many different components around the shoulder but you really need to have a good understanding of where these anatomical components lie in relation to one another in order to able to identify them on a single slice in an mri so the shoulder has many points that stabilize it superiorly we have our bony processes our chromium and our coracoid prevents that humus from riding up we've got the supraspinatus tendon coming up we've got a long head of bicep tendon as well those all prevent the shoulder from subluxing superiorly anteriorly we have ligaments we've got our superior our middle and our inferior glenohumeral ligaments as well as our subscapularis tendon coming anteriorly now we don't work with our arms behind our back so those are ten those are ligaments that prevent the shoulder from going further back but we need to be able to bring our arms forward in front of our body so posteriorly we don't have any set ligaments holding that posterior capsule stable it's our infraspinatus and our teres minor muscles that can stretch that provides stability to the posterior section of our shoulder and that allows us to move our hands freely in front of us we can afford to have ligaments on the anterior that prevent that arm from coming behind us but we need that mobility in front and that's why we don't have glenohumeral ligaments around the back of our shoulder so with all that being said let's get into the mri scans and identify these structures there so let's start with this axial pd or proton density mri of the shoulder and we try and get our bearings first as with any mri we need to understand where we are so we can see we're at the level of the head of the humerus here and if we scroll down we can see that this is actually our glenoid you can see how shallow that glenoid fossa is now the best way to figure out which is anterior and which is posterior is to find our glenoid and then see our coracoid process coming off it's this little hook shape coming anteriorly when we see that we know that this is the anterior portion of our scan and this is the posterior portion of our scan so as we scroll up superiorly we should see our acromion coming into view so we can see our acromion here coming back down to the spine of the scapula there our acromion coming up and our chromium articulates with our clavicle here anteriorly so we want to look at the bones let's look at the acromion sometimes we can have a separate os a part of the chromium that has yet to fuse and either that's because we have a young patient or it's a normal anatomical variant called an osteochromial and people who have an isochromia with this extra bit of bone sticking out that hasn't yet fused to the acromion can be more prone to having some form of impingement and it's good to let our surgeons know if there is an isochromial so we look at the bones there let's scroll down inferiorly and go and look at our glenoid this glenoid should be a good triangular shape like this as we scroll all the way down through it and we should be looking here on this anterior edge especially the anterior inferior edge that we don't have any bony bang cart lesions that's when the shoulder dislocates anteriorly and causes this anterior inferior bit of bone to break off and we can see that this is a normal glenoid as we head up super early let's have a look at our coracoid now you can see our coracoid process now we know the the short head of biceps tendon as well as our coracobrachialis tendon attaches here to this anterior portion of our coracoid and as we scroll down we can see those tendons going into the arm there all the way up to our coracoid process now there's a really important tendon that i mentioned earlier called the karako acromial tendon that makes our coracoacromial arch that then houses our subacromial subdeltoid bursa as well as our supraspinatus tendon so let's try find that tendon it's sometimes easier to go up to the acromion find the tendon here and follow it back down to our acromion so there it is coming off one slice up we can see it coming here it is all the way up up and to our acromion there let's have a look at the humeral head itself start at the superior surface of the humeral head work down we want to see a really round shape especially on the superior portion of the humerus it needs to be really round here we want to look on this posterior surface here for any heel sacs lesion again if you anterior dislocate and you impact this portion of bone on that anterior inferior glenohumeral rim you might get a defect here on the posterior surface of our humeral head work our way down look at this nice smooth surface here interacting with our glenoid fossa we can see our bicipital group here with our biceps tendon in it that is all also normally anteriorly and you can see when we take these mris we want the patient just in slight external rotation to put tension on the subscapularis ligament so we don't have a big floppy subscapularis in front of us keep working our way down we are on a proton density image here so what it does is it it's got long tr's and short test to try and negate or even out some of those t1 and t2 effects so we see we've got relatively bright fat but it's less bright than it would be on t1 and we've got relatively bright fluid if we look in our joint here but it's less bright than on t2 work our way down into the humeral shaft we can see that there's no bony defects we've got a good strong cortex there all the way through let's have a look at some of our ligaments first i'm going to go right down to the inferior glenohumeral ligament these glenohumeral ligaments they are formed part of the capsule the glenohumeral capsule and they're basically just thickenings of those capsules they're not discrete or finite ligaments in themselves they actually form part of that capsule and they're just generally thickenings of that capsule to reinforce the capsule so going down inferiorly we can see that this patient has a pretty thick inferior glenohumeral ligament and as i'll show you now when i drew on that x-ray we had that dipping down of our inferior glenohumeral ligament this is the bit that dips down and then comes back up so we can see there's two layers of this glenohumeral ligament here we've got a anterior section and our posterior as we can call this our anterior inferior glenohumeral ligament and our posterior inferior glenohumeral ligament as we work our way up we should find ourselves getting to the labrum itself or the glenoid fossa can work our way up and we can see our middle cleno humeral ligament here then attaching to the glenoid and as we head up further we can see our superior it's very thin here our superior glenohumeral ligament here it is out here heading down these are a little bit easier to see on some of our other scans let's now have a look at the labrum itself and our axial view is really good at looking at our anterior and posterior sections of the labrum so let's head our way right up to the top of the labrum here this is where our long head of biceps is going to attach and what we want to see is this anterior fold of the labrum here it's nice and dark we don't want to see fluid coming into this labrum or coming right across that label and that might be a tear now we must be cautious our superior and anterior portion of that labrum there are some anatomical variants that allow for fluid to come here what we really want to pay attention to is lower down our anterior inferior section of that labrum that's where our anterior our most common type of dislocation or anterior dislocation happens and that's where we can get our bank cart lesions where we get disruption of that labrum or tearing of that labrum so let's head down we can see the labrum there nice and defined and as we head up we can see it's nice and dark no fluid coming into this label posteriorly sometimes the edge is not as sharp but we still want to see a nice posterior labrum there okay and finally we said we're going to look at the muscle so let's head our way all the way up and this is why i've started on an axial slice because we take this axial slice and then we get our coronal and sagittal planes into the right plane once we know where our supraspinatus tendon runs so as we come all the way to the top we know our supraspinatus runs over the head of our humerus here so we see our head of our humerus we come up we can see our supraspinatus tendon here that's going to go over and attach to the superior part of our greater tuberosity we look at the muscle bulk of the supraspinatus if we've got a supraspinatus that's not working patients will struggle to do that first 15 degrees of abduction so our deltoid when our arm is down by its side our deltoid's got no mechanical advantage it's our supraspinatus that lifts it out slightly then our deltoid takes over so we want to look at the muscle bulk of the supraspinatus and then look at the tendon it should be nice and dark there shouldn't be any bright patches within the tendon so you can see they're coming down nicely there and attaching to the greater tuberosity the superior aspect you can see as we scroll down we'll lose our supraspinatus and it'll be replaced by our infraspinatus below the spine of the scapula i'm going to keep heading down until we're at the level of our humor shaft here as we head up i want to see these tendons coming in so below our infraspinatus is our teres minor so this is our teres minor tendon we can follow it up it's going to wrap around and attach to the inferior portion of our greater tuberosity as i scroll up further in the image we'll see these tendons here of our infraspinatus accumulating accumulating and coming up and also wrapping posteriorly around to the middle portion of our greater tuberosity at this level we should have our subscapularis coming anteriorly so let's go a bit higher as we scroll down we see the body of our subscapularis here a nice big tendon coming around we want to follow that tendon all the way around to our lesser tuberosity here so our subscapularis comes anteriorly it's the only rotator cuff muscle that comes anteriorly and it attaches to this lesser tuberosity here now that we're at this level we can see the bicepital group we can see this dark tendon here our long head of bicep tendon now if this bicep tendon was to dislocate we would inevitably get a disruption of this subscapularis tendon here or rupture of the subscapularis tendon here so we want to look at the integrity of this tendon as well as identify that long head of biceps tendon within the bicipital group let's follow that bicep tendon all the way down into the into the arm so we can see it here as we head up we can see it running in the groove in the groove as we head up it's going to run anteriorly here and attach to the superior portion of our labrum here this is what's known as the biceps anchor and we'll be able to see that better on our coronal views but we can follow that tendon all the way down perfect so it's a lot to cover let's go over to our coronal views so what we want to do is our coronal is not a true coronal if we're at the top of our scan here we can see that our supraspinatus runs anterolaterally here and we want our coronal views to come exactly perpendicular to this tendon so actually a coronal oblique view we want to cut the shoulder like this all the way across so let's have a look at our coronal we can see our supraspinatus here coming across to the superior border of our lesser tuberosity but again we need to figure out where is anterior and where is posterior and the way we do that is exactly the same as an axial we look for that coracoid process so let's find our glenoid and we see what is continuous with the glenoid coming out anteriorly towards us this is our coracoid process we know we are anterior here we can see our caracoclavicular ligament coming there and if we follow across we can see our coracoacromial ligament you see it there from the acromion coming all the way across to the coracoid so now we know we're anterior let's have a look at the bones themselves we can see this part of the clavicle we can see coming across to our chromio clavicular joint here we can look at our acromion coming all the way across to the spine of the scapula you can look at the glenoid fossa here and then look at our scapula coming down and as we come more anteriorly we can look at the coracoid itself you can see the ribs here and the lung fields there so now we know we're anterior let's look at our subscapularis because that's an anterior structure we can see our subscapularis has a really defined tendons coming through wrapping around that anterior part of the humerus and attaching to this lesser tuberosity of the humerus we need to look at the integrity of these tendons and we can see that they're really well defined here it's a normal subscapularis tendon then we can look at our supraspinatus here coming over the top of our humeral head we look at this large tendon coming all the way around we want to see dark tendon coming down and attaching to the superior portion of our greater tuberosity now this light segment here is actually most likely an artifact called magic angle artifact and that's something i will cover in a future video we can see our chromium here with our coracoclavicular ligament and that is just superior to this light structure coming through here which is our subacromial subdeltoid bursa that's a burst that allows that ligament to slide really smoothly as we move our humerus and this can get inflamed it can become very angry looking swollen and it's a structure that we need to identify whenever we're looking at this coronal view of the shoulder again also if we have rupture of tendons or we've got joint fluid coming out that can also leak into the bursa and then we get distension of that bursa not necessarily inflammation but distension of that bursa so we've looked at that ligament let's look at our infraspinatus and teres minor we want to head posteriorly further we can see our acromion we can see the tendon forming on our infraspinatus and lower down our teres minor and we head all the way back we see it wrapping around the posterior surface and the infraspinatus here attaches to that middle segment of our greater tuberosity and our teres minor to the lower segments of our greater tuberosity let's have a look at some of the glenohumeral ligaments here we're going to come anteriorly again we should see folding down here this is quite thick here on this scan this is perhaps a little bit thicker than normal we've got our anterior inferior glenohumeral ligament this is what's known as our axillary recess so if this part of the ligament breaks off the humerus we get a haggle so a human evolution of the glenohumeral ligament or if the glenoid part a vols's awful breaks off we get a gaggle a glenoid a vulture of the glenohumeral ligament and fluid will track either towards the glenoid or towards the humerus depending on which part of the ligament is avulsed it's a little bit more difficult to see but we can see here our superior glenohumeral ligament just before our biceps tendon attaches to this biceps anchor and quite difficult on this coronal view we can try and see our middle glenohumeral ligaments a little bit difficult to see on this view okay lastly we're going to head over to our sagittal pd again start with the bones get our orientation where is anterior and where is posterior we can see we're at the level of the of the head of the humerus so we want to go in and find our labrum as you can see here nicely and then we want to see that coracoid process coming off our coracoid is anterior so we know this is anterior this is posterior this will be our clavicle this will be our acromion so we can see our coracoclavicular ligament there should be able to follow this ligament all the way across to our acromion and it's this arch that i've been talking about our caraca acromial arch that runs from our coracoid through our cricochromial ligament to our acromion that makes us arch over our supraspinatus tendon our biceps long-headed biceps tendon and our subscapularis ligaments what we can see is inferior to this cracoclavicular ligament is our subacromial subdeltoid bursts are running there again let's have a look at the muscles so scroll back and we can find this y shape that we find we've seen that on our approach to shoulder x-rays video i'll link that above if you haven't seen it here we can see our supraspinatus muscle let's follow that muscle all the way through look at the tendon itself we should be cutting this tendon in cross section and we can see that tendon running all the way there it's going to be difficult to see where it inserts because our greater tuberosity is right at the end of our plane but here it is inserting to the superior portion of our greater tuberosity so we want to look for any tears within that tendon itself we can look at our subscapularis it's got multiple start points but it all comes and accumulates anterior to the humerus here running forward and attaching to our lesser tuberosity we can see our biceps tendon is going to be coming up in between those two tuberosities there there's a space here called the rotator interval a supraspinatus tendon the anterior border and our subscapularis tendon this superhero border makes a space here called the rotator interval this is where a lot of inflammation can happen in say a frozen shoulder and our long head of biceps tendon you can see it running here runs through that rotator interval here coming up through and attaching at the superior aspect of our labrum at our biceps anchor so this is a really common review area that we need to look at is known as our rotator interval while we're here we can see our biceps anchor we can see our superior glenohumeral ligament can see the inferior glenohumeral ligaments our anterior and posterior and our middle thickening of our middle glenohumeral ligaments let's follow that long head of biceps tendon here we can follow it back towards us and it's going to come down through the bicipital groove coming up following around and up to our biceps anchor now the last muscles we're going to look at are our infraspinatus and our teres minor you can see the bulk of our infraspinatus here and our teres minor down here we follow the tendon forming here's our teres minor tendon here's our infraspinatus tendon as we become more lateral they're gonna come posteriorly join a little bit with the supraspinatus tendon and provide that stability posteriorly as we come to our greater tuberosity there perfect so it's a lot to take in but the way to approach these mris is to look at the bones look at the ligaments then look at the labrum and the capsule itself before moving on to the muscles and going through each one systematically that way you're going to ensure that you don't miss obvious things or obvious abnormalities on a scan again as with anything arguably knowing the anatomy knowing what's normal is actually more important than knowing what's abnormal lastly i just want to mention we've been looking at pd images where the fluid and the fat are both bright and signal and if you want to figure out is this fluid leaking into a space or is this just a fatty filled space then we can do fat saturated images here i've chosen not to look at those fat saturated images because the fat here gives us nice clear boundaries of our muscles and make things a lot more easier to look at but remember you can always choose a fat saturated image to differentiate between our fluid and our fat in the image so it's a lot to take in i hope you've managed to follow along let me know what other mri scans you want me to do do you want me to do the knee the pelvis let me know and i will ensure that i do it for you all otherwise i'll see you all in the next video goodbye everybody