today we're going over easy ways to learn and remember the muscles of the posterior forearm so to start off with there are 12 muscles in the posterior forearm and they're divided into two different layers the superficial layer has seven of these muscles while the deep blare has five now starting with the superficial layer let's talk about origins all seven the muscles of the superficial layer originate on the humerus two of the muscles originate right above the lateral epicondyle of the humerus four originate right on the lateral epicondyle of the humerus and one originates right behind the lateral epicondyle but basically all some of these are originating off the humerus and they run distally down the forearm now one way you can think about all the muscles of the superficial layer is that these are your beer lifting break dancing muscles unless atrophied and in fact that's the mnemonic we're going to use to remember all seven of these muscles as they run laterally to medially so let me show you how this mnemonic works now the first word in our mnemonic is beer and the b there stands for brachioradialis and that's the first muscle we come to as we work laterally to immediately in this extensor compartment now the reason i chose beer for this demonic is because the brachioradialis is actually considered the beer drinking muscle and there's good reason for that so it originates at the super condylar ridge right above the lateral epicondyle and then it inserts right approximately to the radial styloid process so what that means is that it can help with elbow flexion which of course you need to drink some beer but more interestingly if your hand is supinated and it contracts if you think about pulling this contraction it'll bring you back to neutral to like a beer holding mug holding position again if your wrist is pronated and it pulls it'll again bring you back to that neutral beer holding mug holding position so basically no matter what your hand is in whatever if it's pronated supinated it'll always go back to the booze aka that neutral hand position so that's one reason why it's called the beard drinking muscle and in fact it's the strongest when it's in that neutral wrist position so if you kind of flex your elbow in this neutral position you can feel that brachioradialis really pop out and that's a good way to palpate it for sure okay so beer is for brachioradialis and there's a little bit history there with the beer muscle and the breaker radal so it's a little easier to remember and get the mnemonic started off right so the next word we come to is lifting and the l there reminds us of the extensor carpi radialis longus which again is the next muscle we run into as we're working laterally to medially in this extensor compartment now this muscle originates at the super condylar ridge right below the brachioradialis basically and then inserts on the base of the second metacarpal so what that means is it basically can help you with all the beer lifting things as well so it can help with radial deviation obviously what you need to take a sip it helps with wrist extension which you need to grab a bottle it's always easier to grab something when you're a little bit of wrist extension and then it is a weak elbow flexor again helping you take a sip so it's all coming together with these two muscles beer for brachioradials and the extensor carpi radialis longus for lifting they'll help you with taking a sip okay our next word is break and the bre and break can help us remember the extensor carpi radialis brevis now the brevis basically can do everything the longest can do the real big difference here is that the muscle originates directly off the lateral epicondyle of the humerus and it's not on the supracondylar ridge like the past two muscles it's directly off the lateral epicondyle so you can think of it kind of a break in tradition a break of trends and starting a new trend so the brevis and the next three muscles all originate on the lateral epicondyle and it can help you remember that going forward our next word is dancing and the d there reminds us of the extensor digitorum like the name implies the extension digitorum extends the digits not the thumb but your forefingers it extends those it also helps extend the wrist which you need if you're going to do some breakdancing moves like this or this or of course this so it extends the digits what it does is basically it originates at the lateral epicondyle it comes down the posterior forearm once the tendons reach the metacarpals they start to fan out and they create the extensor hood of each finger so if you've heard of an extensor hood injury that's basically what's happening so this is a very important muscle but actually pretty straightforward our next word is muscles and the m there stands for the extensor digity minimi so what this muscle does is it extends your most minimal digit your basically your pinky finger helps extend that it originates again that the lateral epicondyle runs down and then connects and inserts with the extensor hood of the fifth digit and basically it's a very simple muscle all it does is help you with that pinky extension all right two words to go and our next word is unless the u there stands for the extensor carpi ulnaris so this is the last muscle of our group that originates off the lateral epicondyle directly it then moves down the ulnar side of the forearm which is why it's called ulnaris and it inserts on the base of the fifth metacarpal now if you remember the flexor carpi ulnaris on the other side part of it also inserts on the base of the fifth metacarpal so what you can do is just grab your base of your fifth and then remember the extensor carpi ulnaris attaches there and the flexor carpi ulnaris attaches there so it helps you kind of remember where those insertion points are our next word is atrophied and the reason we use atrophied here is just a little reminder that you shouldn't be doing moves like this if these muscles are really atrophied it also reminds us that the next muscle in our group the anconus is the smallest muscle in the superficial layer so this is a triangular muscle that originates at the back of the lateral epicondyle and connects to the ulna so to get a little idea of where it is what you can do is make a little a with your fingers like that and then put the lateral epicondyle between your knuckles so where your fingers run like this heading towards the ulna is basically a good idea of how the anconus runs all right so that covers the seven muscles of the superficial layer so there's a lot in there of course but just remember these are your beer lifting break dancing muscles unless atrophied so they help you with the beard drinking they help you with the breakdancing and it is a weird mnemonic but when it comes to remembering things the weirder it is the better it works okay so i know you're thinking how can there be more but actually we're almost done we just have to cover the five muscles of the deep layer so in this deep layer there's one muscle for the index finger three muscles for the thumb and then one muscle to supinate the wrist this muscle the supinator is actually the most proximal of the muscles in the deep layer it originates off the lateral epicondyle and also off the proximal ulna so it does have two origin points so to remember all this what you can do is a little trick what i want you to do is place your wrist in neutral have your elbow bent about 90 degrees take your thumb of your other hand and place it on the medial epicondyle then wrap your hand around and place your index finger on your lateral epicondyle you have the rest of your fingers fall flat and just basically hold it there so your thumb basically is representing the pronator teres this muscle basically works in reverse to the supinator and it's a thin tube like muscle basically like your thumb kind of give you an idea of how the pronator teres size-wise is in relation to the supinator the supernatural other hand is a lot broader it's a lot more like these four fingers put together it also has two origin points which are represented by your index finger at the lateral epicondyle and then the rest of your fingers at the ulna so do this little trick and kind of remember where the pronaritarius is and where the supinator is and see how they work in conjunction or basically in opposite of each other one thing to remember is that the supinator is in the deep layer while the pronator teres is in the superficial layer of the flexor component now the supinator is the most proximal of the muscles of the deep layer now let's jump over to the most distal muscle of the deep layer and we'll cover the middle for a little bit later so the most distal muscle is the extensor indices muscle and basically all this does is it helps extend the index finger and it's just latin for index finger so pretty easy to remember now if you want to remember the origin point we have a little trick for that too what you can do is take a look at your finger your index finger and then abduct it as much as you can and then draw a mental line from the nail bed all the way down keep going straight straight straight until you reach the ulna so that's the origin and where this kind of lines up is basically where this muscle will lie so this is where the extensor in a cyst muscle will be on originating off the ulna finally our last three muscles and they all act on the thumb so we have the extensor pulses longus the extensor pulses brevis and the abductor pollicis longus now all three of these muscles basically originate and kind of overlap each other around this mid area of the forearm they then run down and insert on the thumb usually the insertion is the most important part but luckily we have a little trick for that too so when you look at the thumb they have three different bones so we have the metacarpal we have the proximal phalanx and we have the distal phalanx each one of these muscles inserts on a different one of these bones and best of all they run basically in alphabetical order so for the menocarpal our first bone we have an a a there for abductor pulses longus so the abductor pollicis longus inserts on the base of the first metacarpal we then jump to the next bone the proximal phalanx and we have a b the b there is for the extensor pollicis brevis that's where it inserts we then jump to the next bone the distal phalanx and we have an l still running in alphabetical order the l there is for extensor pulses longus and so that's basically where all three of those muscles insert and that's it that covers the muscles of the posterior form i know it can get tricky in there but hopefully some of those tips helped you out stay tuned because we're going to cover the hand next as always thanks for watching and of course good luck on your next test