today we're covering the muscles of the hands of course with a little help from our friends nintendo and bread just just bread as always our goal at memrise medical is to take about an hour's worth of studying and knock it out in just a couple minutes so let's get to it taking a closer look at the hand there are three main areas of muscles the first area is the thenar eminence basically this big pattern muscle directly underneath your thumb secondly we have the hypothenar eminence which is the pata muscle found directly under your fifth digit or your pinky finger and finally we have the muscles found in the middle of the hand dealing and based around the metacarpals now each of these three areas actually has three different muscles or muscle groups in them an easy way to remember this if you're a nintendo fan is just to imagine you slapping a triforce right in the middle of your palm that'll remind you of the three different areas and the three muscles you'll find in each area now there is one extra muscle that doesn't technically fit into any of these compartments so really we can think about it as a triforce plus one but we'll cover that later for now let's check out the muscles of the thenar and hypothenar eminences the good news here is that these areas basically have the same kind of muscles just with slightly different names on each side you'll find a flexor that's closer to the fingers you'll find an abductor muscle that's closer to the edge of the hand and then you'll find an opponent's muscle that runs underneath the other two now the easiest way to remember all the muscles of the two different eminences is with the mnemonic one for all and all for one so for example one for all could stand for the opponent's pulses the flexor pulses brevis and the abductor pollicis brevis all for one could stand for the abductor digiti minimi the flexor digity minimi brevis and the opponent's digity minimi so obviously the order isn't too important here but it'll just remind you of the six muscles you'll find in these two different areas now we can get into the middle of the hand so again there are three groups of muscles in the middle of the hand and the most superficial we come to is the adductor pulses so this muscle is a two-headed triangular shaped muscle that originates off the metacarpals and inserts on the proximal phalanx of the thumb most muscles of the hand insert on a proximal phalanx so this is just one of them next up we have the lumbricals which is actually latin for worms gross and actually these warming muscles are kind of interesting because they're one of the few muscles that originate off the tendons of another muscle instead of a bone so they originate off the tendons of the flexor digitorum profundus [Music] but this is exactly what i'm saying it's like how are you gonna originate off my tendon you know it's my tendon like find a bone like everyone else i know it's it is ridiculous it's like they call them worms no these mussels are leeches leeches they're not here right they're not here oh okay good so to remember the flexor digitorum for fundus just remember if you dig deep you'll find worms aka the lumbricals so to give you a little better idea of how the lumbricals work i have a very very crude model here for you so in blue here this will represent the flexor digitorum profundus tendon in red here we have the lumbrical it arises and originates off that tendon it then runs laterally near the proximal phalanx and inserts on the extensor hood so it does not insert on the proximal phalanx it just inserts around that area on the extensor hood solely so what it also does the rest of the fingers also get a lumbrical so this finger will have a lumbar culture in there another one inserts there and the other one inserts there so when they contract if you can imagine it's pulling it ends up flexing this mcp joint the first knuckle but at the same time it pulls taut the rest of the extensor hood that runs down the finger so what ends up happening is you flex the mcp joint but then you extend the pip joint and the dip joint so if all four fingers do at the same time you end up in this kind of weird hand position and this would be referred to as a lumbrical grip it kind of looks like a sideways l so for their lumbricals things you can remember is that think of the l and lumbrical reminding you that it runs laterally and inserts on the extensor hood and also creates that kind of sideways l shaped grip our last group of muscles is the interossai and there's actually two different types we have the palmer dirac and the dorsal interossai of course interossa in this case is just latin for between the bones and that's where you'll find these muscles between the metacarpals so they originate automatic carpals and then run distally and insert on the extensor hoods and the proximal phalanxes of the digits since they insert on the extensor hoods just like the lumbricals they can do what the lumbricals can do and help create that limbrical grip since they insert on the proximal phalanxes however what they're most known for doing is abducting and adducting the fingers an easy way to remember what each one does is with demonic pads and dabs so the polymer drawsai the p there adducts the fingers while the dorsal and rasai the d adducts the fingers so that covers our entire triforce we saved hyrule we defeated ganon we're doing great but we have to remember our triforce plus one so the plus one there of course is the palmaris brevis this is a very small very superficial muscle that doesn't technically fit into any of our other compartments so it originates off the palmar aponeurosis of the palm and then inserts very superficially into the skin so what they think it does is it contracts and kind of pulls this hypothenar over a little bit the skin at least and kind of helps with gripping things they think it might help with protecting the ulnar nerve if you're kind of hammering things so it doesn't get jangled around or kind of disrupted too much but really no one knows what it does and you'll probably never see it or never notice it's there but hey remember it forever alright so let's close things out with one quick mnemonic to remember the innervations so the vast majority of muscles in the hand are innervated by the ulnar nerve so this is this is basically ulnar territory but there are four muscles that are innervated by the median nerve and the easy way to remember that is with the monic half loaf half so the half l there stands for half of the lumbricals so the lateral two lumbricals are all median nerve then we have the opponent's pulses the abductor pollicis brevis and then half of the flexor pollicis brevis so the flexor pulse of brevis has two heads one gets the only nerve and one gets the median nerve so basically if you're summarizing it the median nerve it's kind of this side of the lumbricals and then most of the thenar eminence so just remember half loaf half and that covers the hand so next up we're going to move into the lower extremity so be sure to stay tuned as always thanks for watching and of course good luck on your next test [Music] you