hello everybody and welcome back to another Anatomy tutorial today we're going to be looking at the anatomy of a wrist in the wrist MRI now this is a talk that follows on from our wrist radiograph talk so if you haven't looked at that talk I'd highly recommend starting there then moving on to the 3D anatomy of the wrist as we're going to be looking at today now a lot of people find wrist MRI Anatomy extremely difficult because there's a lot of structures passing through a very small space now I want to approach this systematically today start by looking at the bones then identify the various different tendons that cross the wrist joint and finish off by looking at the intrinsic and extrinsic ligaments of the wrist as well as the tfcc or the Triangular fibrocartilage complex now for me understanding wrist Anatomy always comes back to understanding the Bony anatomy of the wrist understanding how the carpal bones interact with one another as well as how they interact with the bones of the forearm as well as the metacarpals of the hand so let's start by having a look at this 3D Volume rendered CT scan and I'm going to keep coming back to this image so that we can understand the 3D Anatomy before looking at our axial coronal and sagittal slices in our MRI so we can see that there are two bones of the forearm that then articulate with our carpal bones of the wrist which in turn articulate the metacarpals of the hand laterally we have our radius here and medially our own both our owner and our radius have styloid processes the cells radial styloid the cell illness thyroid the ulna has this indentation here known as ulnophobia and posteriorly we can see our ulnar Groove here where our extends a copy on nara's tendon runs our radius and our ulna articulate with one another at the distal radial ulnar joint and the groove in the radius here that we can see here is what's known as our sigmoid notch a radius itself I've mentioned has a radial styloid it also has this bony outcropping here known as our listers tubercle which is going to become really important when we look at the tendons of the wrist the radius then articulates with two carpal bones our scaphoid bone and our lunate bone this is our radioscaphoid joint and our radial lunate joint this whole joint here is called our radiocarpal joint we can see the scaphoid runs from posterior to anterior as we go from proximal to distal we have a distal pole of the scaphoid a waste of the scaphoid and then a proximal Pole I'll lunate caps decapitate the large bone in the middle of the wrist and our lunate articulates with our triquetrum here out immediately in front of the triquetrum here's our triquetrum we see a sesamoid bone here which is alpaciform bone so the proximal row of the carpal bones here is made up of our scaphoid our lunate our triquetrum and our paciform bone see how the scaphoid comes out anteriorly there's a small bony point of our scale 48 known as the tubercle of the scaphoid and our pisiform also lies anteriorly so those two structures are much more anterior than the body of the scaphoid lunate and triquetoral Bones our distal row is made up of our hamate we can see this outcropping here coming anteriorly is the hook of the hamate the helmet lies next to our capitate here which is capped by that lunate it's easy to see posteriorly here here is our capitate our handmade running medally here then we have two bones sitting underneath the thumb trapped underneath the thumb our trapezoid and our trapezium which lies under the thumb here's our trapezium and posteriorly there our trapezoid bone again our trapezium has this anterior bony outcropping here known as the tubercle of the trapezium so there are four structures that lie anteriorly here on the roller surface our tubercle of our scaphoid our tubercle of our trapezium a hook of our handmade and our paciform bone they lie anteriorly making the shallowed out divot on the roller surface of our wrist which allows our flexor tendons to run through the wrist and we have a sheet of fibrous tissue coming across the frontier known as our flexor retinaculum and it's that space there which is our carpal tunnel which we're going to be looking at later so let's have a look at these bones on an MRI I'm going to start by showing you the coronal images the best way to see all of the carpal bones in one so here's our radius our styloid process of the radius we've got two scalloped surfaces of our radius here I'll scaphoid fossa and our lunate fossa of our radiocarpal joint here here's our distal radial ulnar joint we've got our ulna with our ulna thyroid here and the fovea of the ulna there here's our scaphoid bone running from posterior to anterior our lunate bone which is cupping the capitate bone we've got our triquetral bone here and anterior to that triquetrum is our paciform bone which lies in our flexor copy our Nars tendon that we're going to look at later the distal row we have our bones that lie underneath the thumb our trapezium more posteriorly our trapezoid Which lies next to our capitate bone and then out medially our handmade bone and as we head anteriorly here we can see the hook of the hemate so you can see in this view here are our four anterior structures our pisiform our hook of our hamate our trapezium with the trapezium tubercle here and the tubercle of the scaphoid here are all our flexor tendons running through that carpal tunnel here's our base of our first second third fourth and fifth metacarpals so this is our copper metacarpal joint here so let's move on to our tendons that cross the wrist joint the best way to look at the tendons is to look at in the axial view so we can cut the tendons perpendicular to their course I find it easiest to scroll all the way down to the radius and the ulna so we know exactly where we are here is lateral this is our posterior surface these are our extensor tendons and our abduct attendance here is the roller surface these are all our flexor tendons of the wrist here's our ulna and our radius and I want to head out slowly towards the carpal bones until we can start seeing the carpal Bones come into view then head back into that radius and this is the best view to look at the various different tendons across the wrist now our extensor tendons were our dorsal tendons of the wrist are separated into six separate compartments we've got our first compartment second compartment third fourth fifth and sixth compartments now each compartment contains specific tendons and I want to take you through those various different tendons on the most lateral surface here we have our abductor hypolysis longus it makes sense that the most lateral tendon will abduct our thumb that's our abductor policies longus conveniently the tendons as we go around here alternate between longest bravest longest bravest longest bravest tendons so it's much easier to remember the way in which these tendons come around so in our first compartment we've got our abductor pollicis longus and we've got another tendon here which is our extensor policies brevis a longus and a brevis extensor policies previous we then have two tendons which are our extensor carpi radialis tendons both longus and brevis extensor copy radiolis makes up the second component of our dorsal tendons of the wrist then we have this tubercle here which we looked at earlier which is called lister's tubercle which separates our third compartment from our second compartment at the wrist now there's only one tendon in our third compartment and that's our extensor policy's longest tendon so we had our extensor policies brevis tendon here in compartment one extensor policies longest tendon here lies medial to listers to purple now we can follow that extensor policies longer standard into the hand and we see how it crosses over our second compartment here both our extensor copy radialis brevis and longus tendons and is where that tendon crosses over this extensor policy's longest tendon crosses over compartment two that we can get irritation and inflammation there which is known as intersection syndrome so this is an important area clinically then we can move on to our fourth compartment these are our extensive digitorum tendons both our extensor digitorum indicus the extended digitorum tendons at head to all four digits here laterally to that is a single tendon it's quite difficult to see here it is here is our extensor digital mini me which makes up our fifth compartment of the dorsal tendons of the wrist the last compartment also only has one tendon that's here our sixth compartment which is our extensor copy on nara's tendon now extensor copy all nara's tendon runs in this ulnar Groove here and it actually makes up that posterior surface of our triangular fiber cartilage complex which we're going to look at later so those are our six compartments of our dorsal tendons on the roller surface it's much easier to remember we can see these tendons running on the volar surface heading into the rest and we know that many of these tendons run through our carpal tunnel now earlier I showed you various different anterior structures of the wrist that made up the carpal tunnel here we can see our tubercle of our trapezium as well as our hook of our hemate and we've got this fibrous tissue running between those anterior structures this is our flexor retinaculum which makes up our carpal tunnel here so there are nine tendons that run through the carpal tunnel we can have a look at them now we've got our flexor digitorum tendons both our flexor digitorum for funders and our flexor digitorum superficialis tendons if we actually head out into the forearm a little bit we can see those tendons are flexor digitorum superficiitis and our flexor digitorum profundus tendons then we have one more tendon so there's four profundus tendons four superficiitis tendons and our ninth tendon is our flexor pollicis longus tendon so let's follow those into our carpool tunnel and we can see how there's not much space here the other structure that you'll see here is our median nerve running within that carpal tunnel you can see how if there's inflammation here or swelling how we can get impingement of that median nerve giving us carpal tunnel syndrome and surgeons may need to cut this flexor actinaculum to make more space there now there are two other flexor tendons of the wrist that don't actually go through the carpal tunnel the first is our flexor carpi radialis tendon that actually heads into the flexor retinaculum you see how it runs within the flexor retinaculum here it heads out underneath the tubercle of our trapezium and goes all the way into the hand and actually inserts onto the base of the second metacarpal bone here you can see it here inserting onto the base there around the underneath the tubercle of the trapezium and into the forearm here now the last thing in here is our flexor copy on nara's tendon which heads out towards our pisiform bone and actually encapsulates that pisiform bone that this form is a sesamoid bone and that then has a ligament to the handmade bone and to the base of the fifth metacarpal bones so we've seen our median nerve here we can see another nerve on the medial surface here which is our ulnar nerve we can see our ulnar nerve here running with our ulna artery running within this canal and this is known as gion's canal we can also see if we head out into the forearm again we can see our radial artery and our radial nerve here our radial artery as we head into the hand will then extend posteriorly to the dorsal surface of the hand so those are the major tendons that I want to discuss now we're going to move on to the ligaments of the wrist now many people find the ligaments extremely difficult to understand and I want to show you where those ligaments run on this 3D rendered CT first and then we're going to head into the MRI now a lot of these ligaments are quite difficult to see on an MRI an MRI I've got here is quite thick slice and we're going to miss some of these ligaments but I want you to understand where they run the ligaments really are structurally important in maintaining the Integrity of the wrist maintaining the 3D relationship of the carpal bones to one another now we can separate the ligaments of the rest into intrinsic ligaments and extrinsic ligaments intrinsic ligaments connect carpal bones to carpal bones extrinsic ligaments are basically thickenings of the joint capsule and they connect our bones of our forearm our radius and our to the bones of the rest the carpal bones so let's start by looking at the intrinsic ligaments of the rest and they're only three ligaments that I want to draw your attention to here we can see our scaphoid our lunate and our triquetarum bone here making up the proximal row of the rest as well as this pessiform bone now there are strong ligaments between our scaphoid and our lunate known as our scapholunate ligament and between our lunate and our triquetium our luno triquetral ligaments now this ligament runs from the dorsal surface here and beneath and wraps around to the roller surface here and actually three components of that ligament as it wraps around we've got a roller component and into osseous or membranous component at the proximal surface and then we've got a dorsal component now the dorsal component of our scapholunate ligament is perhaps most functionally important of that and as it heads around it starts thicker posterity and as it heads around vularly or anteriorly it becomes thinner that ligament the opposite is true for our Luna triquetral ligament which starts out thick on the volar surface gets thinner through the intraosseous or membranous Surface and it becomes quite thin on our dorsal surface here those are the two main intrinsic ligaments we also have our scapho trapezo trapezoid ligaments and that forms an stt joint escape a trapezo trapezoid joint here which we'll also look at so let's have a look at those intrinsic ligaments on our MRI scan now on the proximal surface of these I said there's a membranous or a intraosseous surface of that ligament it's not actually a true ligament it's actually fibrocartilage heading out on these proximal surfaces here so we can see our scaphoid bone our lunate bone and we can see that intraosseous or membranous portion of our scapholunate ligament here and as we head out to our lunar triquetral ligament we can actually see our intraosseous or membranous portion here can take many different shapes we can have a broad triangular shape we can have a linear shape it actually functioning is not so important when we're looking at this intramembranous section now if you want to see our dorsal and alvolar ligaments here it's best to look at it on an axial slice we might catch some of those ligaments here we can see running from our scaphoid to our lunate and on the roller surface it's a bit more difficult but here's our voila scapholunate ligament so our dorsal scapholuna ligament and although less scaffolding ligament let's look at those on the axial slices it's much easier to find now most important when looking at the axial slices is realizing where you are are you in the proximal row or are you in the distal row of our carpal bones and again the easiest way to do that head out into the forearm scroll up slowly until you see those carpal Bones come into view you know the first carpal bone here is our lunade and our scaphoid bone laterally here and heading out to our triquetrum here you can see how the lunade cups that capitate here our capitate coming into view there so dorsally the strongest part of our scaven lunate ligament is this dorsal portion here we can see it's thickened this is our dorsal scapulunate ligament anteriorly we can see also there's the anterior scapholunate ligament let's look at our Luna triquetral ligament dorsally it's very thin anteriorly we've got this thick band here the vola Luna triquetal ligament then I said we've got our stt joint so let's find our scaphoid bone sometimes it's easier to find the lunate this Crescent shaped bone cupping the capitate and then head out towards our scaphoid bone which we know goes from posterior to anterior and here is our stt joint our scapho trapezo trapezoidal joint there and there are ligaments that attach these intrinsic ligaments which I'm not going to show you on this MRI now let's have a look at the extrinsic ligaments of the wrist the extrinsic ligaments attach the radius and the ulna to the carpal bones they're both volar extrinsic ligaments and dorsal extrinsic ligaments let's start by looking at the vola extrinsic ligaments because we are on the formula surface here now we've got a ligament that comes from this lateral surface of the radius goes over the waist of the scaphoid and attaches to the capitate here this is our radioscapocapitated ligament then we have a ligament slightly more meatly running from the radius to the lunate and to the triquetrium here this is our radio triquetral ligament also known as our long radiolinated ligament now our long radiolinate ligaments coming from the radius to the lunate and to the triquetarum we have a short radiolunate ligament here coming from the radius to the lunate so we've got a long radiolunate ligament going from radius to lunate to triquetarum and a short radial lunar ligament going from radius to lunate then we've got ulna-sided ligaments which are also extrinsic Viola ligaments it's our ulnar triquetral ligament our ulnar capitate ligaments and our ulna lunate ligament and those three ligaments also become really important to make the anterior surface of that triangular fibrocartilage complex which we're going to look at next so we've got these vola extrinsic ligaments let's go have a look at them on our MRI these can be quite difficult to see especially on this coronal plane but let's go and find the volar surface of the wrist now many people struggle to figure out whether they're lying dorsally or on the roller surface when they're looking at pronal images and the way you want to do it is find those four anterior structures find the trapezium the scaphoid the hook of our hemate and our pisiform bone these are our flexor tendons we know we're on the roller surface then scroll posteriorly or dorsally until you can see your radius come into view now we can see these fibers running across here a little bit difficult to see from our radius to our lunate and then heading out to our triquetrum these fibers here are our long radiolunate or our radio triquetral ligament we can then also see these short radiolinate fibers running here we also have a radioscapocapitate ligament we can see it coming from the most lateral surface of our radius here by our radial styloid running around the waist of our scaphoid here then coming out to the anterior roller surface of our wrist and attaching to the capitate here you can see it wrapping around that bone quite difficult to see in the coronal plane then let's go on to our ulna extrinsic roller ligament we've got our ulnar triquetral ligament running from the ulnar styloid here to the triquetarum quite difficult to see will have an ulna lunate ligament that we might catch the anterior surface of here this is potentially the only lunate ligament coming from this ulna heading across towards the lunate there on the volar surface and we have an ulnar capitate ligament which might be quite difficult to see on this plane let's have a look at on the axial plane and these ligaments all merge into one and you can see how they're quite continuous with one another they make up this thick band here these are our extrinsic volar ligaments and we can head down towards our radius our ulna we see our radius will give off our radial lunate our Long Radio Illuminator heading towards the triquetrum here our owner will give us our ulnar triquetral ligament you can see it just coming off there on the surface here to the triquetarum as well as our ulnar lunate ligament all fusing to form this thick band this thick ligament here now let's look at our extrinsic dorsal ligaments of the wrist we have our roller surface of this 3D rendered diagram let's go to the dorsal surface now they're actually only three ligaments that I want to look at on this dorsal surface we've got a ligament that attaches our radius to our owner that's our dorsal radio ulnar ligament and actually what I failed to mention on the front side here was our volar radial Islander ligament which I'll show you when we look at our tfcc complex so we've got a dorsal radial ligament then we have a ligament coming from our radius to our triquetrium that's our dorsal radio triquetral ligament and then we've got a ligament that extends along the posterior surface of this wrist which is known as our dorsal intercarpal ligament it heads from the triquetrum to the scaphoid as well as extending branches towards the trapezium and the trapezoid bones so let's look at those on our MRI I'll start by having a look at the coronal section again if we scroll anteriorly we see those four anterior structures we want to scroll in the opposite direction get to the posterior surface here and actually we can see very nicely coming into view here is our dorsal radio triquetral ligament running from the radius to the posterior surface of the triquet room here then we can see these fibers running across from this posterior surface of the triquetrum heading towards our scaphoid bone here this is our dorsal intercarpal ligament here and begin with the eye of Faith see some ligaments going towards our trapezium and our trapezoid as we head more posteriorly we can see there's a ligament running from the radius to the ulnar styloid coming across here this is our dorsal radio ulna ligament we can also see our volar radio only ligament here perhaps coming from the radius to the ulna now those make up the posterior surface our dorsal radial on the ligament the posterior surface of our tfcc our triangular fiber cartilage complex which we're going to look at next as well as the anterior surface which is made up by the volar radial ulna ligament so let's go ahead and look at that tfcc the Triangular fibrocartilage complex of the wrist and the tfcc lies above the ulna here and what it does is it provides stability to the wrist as well as transferring weight axial loading through the wrist away from the ulna into this broader based radius here allows the weight to go through here now the tfcc is also like a meniscus within the knee it provides some cushioning between the carpal bones and the ulnar itself so let's look at these structures we've already looked at the anterior surface which is this voiler radial ulnar ligament and we've looked at the posterior surface which is this dorsal radio only ligament more posteriorly we've got our extensor copy our niras tendon here and that sheath of this tendon as we follow it across here provide some posterior surface of this tfcc anteriorly we looked at those volar extrinsic ligaments of the wrist our owner triquetral ulnar capitate and ulna lunate those also provide anterior wall of this tfcc complex within the complex itself we have this triangular fibrocartilage disk proper here which is this by concave shaped structure which is hypo intense to these surrounding structures you can see it attaches to the radius itself onto the cartilage we've got a hyper intense relative to the disc itself structure running along here this is the cartilage this is not a tear of the tfcc disk proper this is the radial attachment and then we've got medial attachments which attach to the ulna itself we've got both a fovial attachment so let's go to the ulnophobia here quite difficult to see on this image but we've got this extending down to the fovea there's no cartilage here there should be a strong connection between the Triangular fiber cartilage ligament and the phobia and quite difficult to see on this image but we have a ligament heading towards our styloid process as well coming across here so this triangular fibrocartilage disc gives off two triangular fiber cartilage ligaments one heading to the fovea and one heading to the styloid process which unfortunately we can't see too well here above that triangular fiber cartilage disk proper is this fibrocartilaginous structure here known as our ulna meniscal Humalog that ulnar meniscal Humalog it's a fibrocartilage tissue running superiorly to this TFC disc proper and it fuses with this ulnar collateral ligament which is basically a thickening of the synovial capsule here so they're trying to get a fibrocortis disk is a really important point to look at when assessing the MRI because we can get degenerative or traumatic changes within this disc now many people find this tfcc complex quite difficult to conceptualize and I like to think of it as different borders housing around this disk as well as the Triangular fiber cartilage ligaments and the ulnar meniscal Humalog so our lateral border here is our only collateral ligament our medial border is the attachment of the disc to the radius here and our posterior surface is made up of that extensor copy on Nora's tendon sheath as well as our dorsal radial ulnar joint and the anterior surface is made up of that voiler radial ulnar joint as well as those extrinsic ligaments coming off the ulna towards the carpal bones our ulna triquetyl ulnar capitate and ulna lunate ligaments now I know we've gone through a lot here and there's lots of anatomy running through a very small space but again if you approach the risk systematically you start by having a look at the bones understanding where they are in relationship to one another then look at the tendons the six different dorsal compartments looking at the Ebola tendons our flexor tendons running through our carpal tunnel as well as our flexor copy alnoras and flexor copy radiolis tendons then you can move on to the ligaments our intrinsic ligaments connecting carpal bones to one another our scapholunate ligament lunar triquetral ligament askevo trapezo trapezoidal ligament and then look at our extrinsic ligaments our volar surface ligaments our radio capitate or radio Escape or capitate a Long Radio lunate our short radial lunate as well as our ulnar triquetral only capitate and only lunate ligaments as well as our vola radial ulnar ligament then move on to the dorsal surface no radio triquetral our dorsal intercarpal ligaments as well as our dorsal radio ulnar ligament go through those systematically every time you go through an MRI try and identify these structures and then you'll start gaining a better appreciation for where you are in the wrist and which structures you are looking at if you made it to the end of this video well done it's a lot of content to go through I really do hope you find these talks helpful if you do I would appreciate it if you consider liking this video as well as subscribing to the channel for more anatomy and physics videos and until next time I'll see you all goodbye