hello everybody and welcome back to another Anatomy tutorial today we're going to be looking at the anatomy of the elbow joint on an MRI scan now some of the anatomy here is going to be assumed knowledge and if you feel like your elbow anatomy is a little bit sketchy I'd highly recommend going back to the Elbow radiograph talk that I given before we're going to cover a lot of what has been talked about in that talk here in multiple planes on an MRI so we'll start by having a look at the bones then we'll look at the tendons and the various muscles that are associated with them before moving on to the of the elbow joint and then finally looking at some of the nerves that cross the elbow joint so let's start by having a look at the bones we know that they're three bones that make up the elbow joint our humorous superiorly and disly we have our radius on the lateral side and our alna on our medial side here the distal humoris can be separated into multiple different sections depending on the ocation centers that created that distal humorus we've got our lateral our medial epicondilite of the elbow joint then we have our tra which articulates with that tra Notch of the on the bone and then we have our capitellum our small head here that articulates with the radial head at our radio capitella joint so we have our radio capitella joint laterally our alna humoral joint medially and our proximal radio alna joint here where that radius can rotate around in this pivot fashion and articulate with this proximal elner here so our radial bone can be separated into different sections we have our radial head here the part with a shallow fosser that articulates with that capitellum our radial neck heading off towards our radial shaft and we can see immediately here this radial tuberosity where our biceps Breaky tendon is going to attach our elner bone can also be separated into multiple Parts if we go right posteriorly in the image here we can see our elron posteriorly our TR coming round to our coronoid process anteriorly here and then the ener bone heading down towards the ener shaft as well as having our alner tuberosity here where our brais tendon is going to insert and we're going to have a look at that when we look at the tendons if we look at this in the sagittal plane we're cutting the humorus here in the sagittal plane you can see our tra here our tra Notch of the Elna with our coronoid process and posteriorly our elron we can see there's a depression a shallow depression here called our elron fossa that's filled with fat and we know that if we get a joint diffusion and that fat pushes away out of that fossa we get a radiological sign on our radioraps called the sail sign posteriorly and anteriorly as well this fat should be tightly opposed to the Bone here like we can see here this allows that elron when we extend our arm outward to go into the space without impinging on important structures as well as providing some cushioning the same happens when we Flex our arm this coronoid Pro process can go into the coronoid fosa which is this fat filled space now there are multiple tendons or muscles that cross the elbow joint to allow for extension and flexion of the elbow joint our major flexes of the elbow joint are our anterior upper or brachial section of the appm we all know our biceps brachy biceps meaning two heads we got a long head that we looked at in our shoulder MRI torque which heads all the way to that super glenoid tubercle and then we've got a short head coming to our coracoid process of our scapula they then head down into the upper arm and fuse to form our biceps Breaky tendon we know that biceps Breaky tendon crosses the midline and attaches to the radial tuberosity so let's find this radial tuberosity here and we should be able to follow the biceps Breaky tendon up as we had anteriorly can see those two heads of the biceps Breaky muscle coming together forming the biceps Breaky tendon that heads its way down to the radial tuberosity there our elner tuberosity has our brachialis muscle now the origin of our brachialis muscle is on that anterior surface of our humoris and that tendon heads across the elbow joint and inserts onto the enna tuberosity so let's find our enna tuberosity we know it lies anteriorly to the Elna here it's quite difficult to see it on the coronal plane I'll show you it in the sagittal plane now as we head up we should be able to see a tendon forming here following my mouse across and that tendon is our brachialis muscle tendon let's have a look at that on the sagittal PD it's much easier to see here's our brachialis coming from that anterior portion of our humoris and inserting onto that Ela tuberosity we should be able to head out more laterally and see this large biceps Breaky tendon that attaches to that radial tuberosity here's our radial bone that medial surface of our radial tuberosity heading across there we know our extensors of the elbow are our triceps triceps three heads so we've got a lateral head we've got a medial head and in between those we've got the long head of the triceps now if we find our elron we know that the triceps tendon attaches to that elron you'll see there's a tendonous attachment posteriorly and then a muscular attachment slightly more anteriorly onto that electron so it's really important to assess whether the tear involves both the muscular and the tenderness section or just a partial tear through either the tenderness or muscular sections this is our lateral and our long head of tricep making this tendonous section and then our medial head the one that lies deep to the lateral and the long head of triceps then gives us this muscular attachment onto the elron here so those are the major flexes and extensiv of the elbow but we have a couple of muscles that cross the elbow that are involved in wrist flexion and extension and those actually don't contribute to flexion and extension of the elbow their action is at the wrist joint the reason they don't contribute to flexion and extension of the elbows because they lie on the lateral portions of this elbow we know the elbow is a hinge joint we don't get lateral movement of our elbow so any muscles going across that lateral section are not going to allow us to move the elbow in a vola or vulgus movement these muscles then cross the wrist joint and allow for flexion and extension of both the wrists and the fingers so let's start out laterally now as with any joint in the body our tendons lie lateral and our ligaments lie medial we our ligaments keep the bones together we don't want tendons interfering with the ligaments there our tendons are lateral to those ligaments to allow movement Across The Joint so let's have a look at our lateral feel it's the lateral compartment and posterior compartment of the forearm that flexes when you extend your wrist the medial compartment is involved in flexion so here laterally we have our common extensor tendon you can see it out here laterally there's a small bit of hyperintense signal here separating this common extens of tendon from our ligaments of the elbow we can follow that common extens ATT tendon down into the forearm there the common extensor tendon is what gives rise to our extensor carp elaris our extensor digitorum and our extensor Digi minimi so three muscles are arising from this common extensor tendon origin as you can see superiorly and more laterally to this we also have other muscles that originate from slightly higher up than this lateral epicondyles that's where our bracho radialis originates which allows for some flexion of the elbow as well that inserts into the sty process of the radius here distally a bracher radialis originates higher up there and it's at that point as well where our extensor carpy radialis longus and bravous also originate they don't actually come from this common extensor tendon so that's our lateral portion the main tendon here is our common extensor tendon if we go to the medial side we can see our medial epicondyle we're on the side of the Elna here and we should be able to see the common flexer origin here of our tendons here so you can see a tendon coming from the most medial part of this mediate epic condal and that heads off into our flexes of the forearm you can see this muscle wrapping around here our pronator teres terries meaning round it's our round pronator that means we've got another pronator which is more distal in the forearm which is our pronator quadrus our Square pronator pronator teres is the first one that's coming off that common Flex ATT tendon origin here we also have our flexa copy alarus our flexor copy radialis we've got our flexid digitorum superficialis and our palmaris longus all coming from that common flexor origin of the medial epicondyle a tendon here so our tendons lie more superficial than our ligaments let's have a look at some of the ligaments that provide stability to this elbow joint we've got lateral ligaments and we've got medial ligaments I'm going to start on the medial side because it's a little bit more simple and we're at the right position to have a look at this ligament you can see the coronoid process here of the elner bone and this most medior little bit here is what's known as our Sublime tual and that's what gives rise to the anterior band of our alner collateral liament the elner collateral ligament comes from the Elna and heads off towards the medial epicondyle tendon here the largest part of the eloc collateral ligament is this anterior band and it's the one that we're going to be looking at most when we're assessing for injuries if you've got people who are throwing a lot and they're giving a lot of vulgus pressure on that elbow it's this tendon that experiences a lot of the force coming through it baseball players or cricketers that are throwing like that they get lateral compressive symptoms on this side and then we get tears in the anterior band of our own the collateral ligament on this side you'll see that the signal here is very hyper intense at that Sublime to tual here there's a good connection here and we mustn't see fluid coming in between this elner colateral ligament and our Sublime tuberal that would be what's known as the reverse T sign which suggests a tear at this point as we had more proximal or superiorly in the image we can see the signal becomes a little bit more heterogenous before it inserts here below the medial leond and that's normal for the anterior band of the El no collateral ligament if we were to head a bit more posteriorly this Al collateral ligament thins out like this and this this is the posterior band of the elateral ligament it's almost continuous it's just a thickening anteriorly then it heads out posteriorly and gets thinner and thinner there's also a transverse aloc colateral ligament which kind of forms a triangle with these are anterior posterior and transverse it's not really a ligament that you look at much on an elbow MRI it's a very thin band that doesn't actually cross the joint just comes from this medial portion of the eler bone and heads out towards the lateral portion here of the elron posteriorly you might see a little bit of it there let's head on to our lateral ligaments here we can see our common extensor tendon here separated from this band here which is our radial collateral ligament our lateral collateral ligament our radial collateral ligament heads off from this lateral epicondilite tendon and insert into the annular ligament that we talked about in the X-ray radaph talk that that wraps around the head of this radius we're going to have a look at axial Imaging when we finish off this talk looking at all the various bits of anatomy and we'll see that annular ligament wrapping around this radial head allowing for that pivot motion while keeping that radial head in place so we got our radial collateral ligament that then inserts into our anular ligament now our anular ligament heads off from the sigmoid Crest on the elner bone here both a vola and a dorsal sigmoid Crest which I'll show you again on the axial and it wraps around so it inserts in both the vola sigmoid Crest and the dorsal sigmoid Crest there's one more ligament that provides stability at the elbow joint and it's a posterior ligament that heads from our elner bone posteriorly wraps around the posterior portion of our radial head and then heads up and inserts onto that lateral superator Crest we're going to look at the superator muscle that comes off here and we can see this ligament heading out superiorly and laterally wrapping around the radial head and then heading up towards this lateral Epicon here so we can follow it let's follow it down and we can see it coming down into that Al the bone there so let's have a look at an axial PD here and consolidate all of that knowledge bring it all back together we can start superiorly in the humorous here and head down we know that this here is lateral cuz we can see this anconeus muscle here and our alna nerve which we're going to look at here is medial so our anconeus muscle lateral here if we scroll down further we should see our radial head come into view there look at this anular ligament heading all the way around the radial head there this dark structure here from our vola sigmoid Crest heading all the way around to our dorsal sigmoid crest of the elab bone we can see the electron here of the eler posteriorly and as we head up we should see this triceps tendon both the muscular and the tendonous portion you can see the heterogenous signal in this tendonous portion of our triceps tendon and that's normal for the tricep let's go up into the Brach your portion of the Upper Limb and start at our biceps Breaky here we should be able to follow this tendon down and that will insert into our radial tuberosity follow it down there is our radial tuberosity lying on the medial surface of the radius again if we follow that up we should be able to look at our brachialis muscle and the brachialis tendon that heads down into our enna tuberosity we can see it inserting there onto the en tuberosity you can see how the tuberosity is more anterior our radial tuberosity is more medial here let's have a look at some of the ligaments and tendons on the lateral portions of the image so we've got our radial side here so we know that this is our lateral Epicon we should as we scroll down slowly see a separation of our common extensor tendons here and our radial ligament here so our common extensor tendons Go off into the extensors of the arm our extensor carpy alarus our extensor Digi minimi and our extensor digitorum further up we've got our extensor copy radialis longest and bravest as well as our bra your radialis which is this large muscle line anteriorly here on the medial side here we can see our common flexer tendon origin which gives rise to those five muscles our pronator terries here our Flex ay alarus flexy radialis Al palaris longus and our flexa digitorum superficialis muscles it's not necessarily important to remember all of these muscles some of them have a distinct appearance like the anonas like the large braco radialis and like this muscle that wraps around the radius here as our superator muscle coming from that supernat Crest that I talked about earlier where our lateral elner collateral ligament you see it coming there lateral Al no lateral ligament wraps around the posterior portion of the radial head here and then heads up towards our lateral epicondilite lateral side we've got our lateral olar collateral ligament we've got our radial collateral ligament and we've got our anular ligament on the medial side we've got our nner collateral ligament that separates into three separate sections our anterior bundle posterior bundle and that transverse section if we go to our medial epicondyle of our alner collateral ligament and here we can see that thin posterior bundle heading off there and it's very difficult to see our transverse ligament that heads from that coronoid all the way around to the electron that anterior bundle we know inserts into the sublime tubercle of Al coronoid process what else we need to look at the last thing we need to look at is the nerves that cross the elbow joint the easiest nerve to look at is this medial nerve posteriorly here that comes through our cubital fosser which is known as our nna nerve nerve this is our nerve you can see how superficial it is this is our Funny Bone if we were to apply direct pressure on here putting pressure on that en nerve and our medial epicondilite pain shooting up through our arms that's our ener nerve heading down it gets embedded in this flexor copy alarus on this side and heads into the forearm let's look for our radial nerve we know that our radial nerve starts posteriorly and then it wraps around the humoris laterally and then heads into this anterior compartment the best way to find it is to go to the elbow joint and see this large breaker radialis muscle here posterior and slightly medial we should see these two radial nerves they split here into a superficial and deep branches and as we head down further we should see that this superator muscle comes around between the breaker radialis and the superator muscle here we get that deep Branch heading backwards giving us our posterior into oio nerve here on the medial side let's head back up to the elbow joint find our medial epicondyle tunnel supplying muscles of the hand there and another that heads off as the anterior into osus branch so those are the three main nerves often it's difficult to see the nerve but you can see the perineural fat these are our axial PD's nonfat set images so our fat gives us good contrast for our tendons for our ligaments as well as our nerves here so that's a Whistle Stop tour through the major structures that cross the elbow joint obviously when you are looking for pathology you need to go and have a look at marrow signal you can look at your PD fat SATs as well looking at the marrow looking at the bones looking for various fractur and I just want to touch on two things before we end off that people commonly get confused with the one is we can see our bone here on the sagittal PD our lecron coming posteriorly and this coronoid process coming anteriorly you see the articular surface here of our trar Notch then there's a disruption here and then we get a continuation of that Cottage there this is normal this is what's known as our tra Ridge and if we were to look at the articular surface of the elron and that coronoid process in that trar Notch there's a small gap between that cartilage there which is normal that small Gap gets bigger as we head out laterally see how much bigger it gets and if we head out immediately here it also gets bigger so on the peripheries that tra Ridge becomes bigger that's not a foreign body that's not a disruption of the cartilage there lastly if we head out towards our capitellum so we can see our radial head here that articulates with our capitellum we can see the articular surface of this rounded part of the capitellum we get a flattening out here at the posterior port of the capitellum where there is no cartilage that's completely normal when we cut this in coronal sometimes we will see radial cage and no capitella cartilage let's see if we can see it here we can see let's go sorry let me go posteriorly see how we've got cartilage here on our radial head but we've got no cartilage here on our capital and that's normal that's just the posterior surface we haven't lost any articular Cartage on that capitellum so we've gone through the elbow joint looked at the bones the ligaments the tendons some of the nerves that pass through there I hope this has helped you at least approach an elbow MRI once you know the anatomy well then you can figure out what is wrong within an image has the Elna nerve dislocated out of this Capital Groove here have we got a fracture of this coronoid process because of a posterior dislocation of the eler there we know what normal Anatomy is which will allow us to look for pathology in the future so I hope this helped I'm going to move on to the Foot and Ankle next week starting with the radio graph then heading to an MRI so be sure to check those out next week and I'll see you all then goodbye