welcome to the lab everyone I'm Jonathan benan with the Institute of human anatomy and today I want to show you something really cool on this dissection of the right Upper Limb and I want to give you some numbers here 4 20 now 420 might mean different things to people participating in certain recreational activities however in the land of anatomy we like to say 420 because there are four muscles in the brachium or the upper arm but down in the anti brachium or the forearm they are 20 muscles now why is there such a large difference in the number of muscles between the brachium and the anab brachium and of course what is the point of me bringing this up well the muscles of the brachium mostly just mobilize the elbow and we only get a few movements at the elbow it will move this way in flexion and extension and then the radial owner joint within the elbow can also move like this pronation and supination so fewer movements require fewer muscles but as we go down to the anti brachium these muscles are going to mobilize the wrist in all sorts of different directions and many of the tendons that we'll see in just a second will move down into the hand and mobilize the fingers which requires more muscles to create all these specific movements and some of these muscles Bend our fingers and we actually call that flexion of the digits and these muscles help us to grip things like when we try to open a bottle hang from a pull-up bar or pull on weights and just like every other muscle in the human body these muscles can be trained to get stronger and this would in turn improve our grip strength but with the exception of say like a rock climber how much time do you actually spend doing specific workouts for these muscles probably not as much as you do with the fewer muscles that are found in the brachium like the biceps and the triceps but the question is should we focus more on our grip strength well some think that we should because there appears to be an association with grip strength and aging and Longevity some studies show that maintaining grip strength is associated with a lower risk of Falls fractures and overall Frailty so what exactly is it about the grip strength that positively influences aging and Longevity is this some magic bullet to aging that means all of us should take up rock climbing or incorporate some sort of grip strength protocol into our exercise program well we're going to find out what all this really means and of course look at some really cool anatomy in the process so let's do this so to understand and grip strength we'll want to learn about the muscles that contribute most to grip strength the first one is the flexor digitorum superficialis and you can see that I pulled that up and isolated it with the probe and pushed some of the other muscles out of the way but if you break down that name flexor digitorum superficialis it tells you a lot about this muscle it's going to flex the digits specifically the pointer to the pinky finger and it's the more superficial of the flexors and we'll see a deeper flexor in just a minute and look at how cool the meat of the MUSC muscle is or that muscle belly how it's located in the anti brachium but then you can see the tendons start to emerge and then those tendons will pass through the carpal tunnel a little bit more on the carpal tunnel in just a second but once those tendons pass through the carpel tunnel you can see that they'll flare onto each individual digit or finger and an important distinction with this flexor Tor superficialis muscle is that the tendons insert onto the middle fangi this other tendon that we'll talk about in just a second will make it all the way to the fangi but keep that in mind with the flexor digitorum superficialis only goes to that middle fangi so this muscle can Flex the metacarpal Fingal joint which I know is a bit of a mouthful but this bone here is called the metacarpal bone this Bone's the fangi so the joint in between is called the metacarpal Fingal joint or the mCP joint what you would think of as your knuckle this muscle can also Flex the proximal interphalangeal joint again long joint names here but this is a fangi this is a so the joint between is called the interial joint or the IP joint and because there's two IP joints one here and there we do have distinguish between the two the one that's closer to the point of origin is called the proximal interial joint the one that's further is called the distal interphalangeal joint and so again because that flexor digitorum superficialis inserts onto that middle fangi it cannot to every Rock climber's dismay it cannot Flex that that distal interanal joint when they're hanging from some creepy uh not creepy crimpy handhold but this is where the next muscle comes into play the flexor digitorum profundus the flexor digitorum profundus is deep to the flexor digitorum superficialis and profundus just means deep like profound but the tendons of the flexor digitorum superficialis are actually right here we've cut them away and just to orient you more fully this is actually a left arm and left hand compared to the other dissection that we saw that was a right and we removed more of those superficial muscles but like the tendons of the flexor digitorum superficialis the tendons of the flexor digitorum profundus also travel through the carpal tunnel and they will flare out onto the individual digits but the difference is those tendons will go to the bases of the distal fanges on all four of those fingers and if you look really closely you can see how cool this is that's the tendon from the flexor digitorum superficialis that gets split by the tendon of the flexor digitorum profundus which again makes it through that distal fangi and gives us the ability to bend or Flex that distal IP joint that last joint there so putting these two muscles together they are both engaged when wrapping our fingers around large holes like a barbell or a pull-up bar but again when someone is only able to grip something with their fingertips it is the flexor digitorum profundus that is predominantly activated to flex the distal joints and therefore why strength in this muscle is so important the last muscle I want to mention is the flexor Pocus longus pocis means thumb so this is the longer muscle that flexes the thumb there is a flexor Pocus brevis that you can see here in the hand just this little muscle here but we're just going to focus on these three larger muscles when it comes to grip strength and obviously the thumb gets involved in gripping certain items but the tendon of the flexor Pocus longus also runs through the carpal tunnel and it will insert onto the distal fangi of the thumb flexing that one IP joint or that one interfon gal joint that we do have in the thumb and just a real quick note on the carpel tunnel that now gives us nine tendons that run through the carpal tunnel and there's also a nerve that runs through the carpal tunnel called the median nerve and if this tunnel gets swollen or inflamed this can compress the median nerve and can cause the symptoms of carpal tunnel which we have a longer video of that that I'll link it at the end of this one so even though it would be really cool to be able to grip tiny little cripper holds while climbing or do a dead hang for over 2 minutes maintaining grip strength also plays a crucial role in our daily activities as we age maintaining a strong grip helps with tasks such as opening jars carrying groceries and maybe even helping to prevent Falls if you were able to grasp a hold of something before going down to the ground and so grip strength is increasingly being recognized as a valuable indicator of long-term Health and Longevity and some researchers have even found that having a weak grip is associated with higher risks of cardiovascular diseases diabetes and even cognitive decline but what does this really mean does it mean you need to go nut strengthening your flexor digitorum profundus and superficialis and flexor pois longus to save your heart prevent diabetes and make you some super ageless Wonder well kind of having better grip strength and better outcomes with aging and longev is an association or a correlation not a direct Cause And what I mean by this is let's say you did have a super strong flexor digitorum profundus that doesn't magically by itself make your heart more healthy improve your metabolic health and reduce your risk of diabetes directly yes it makes it so you can hold on to something more forcefully and may help prevent Falls in certain scenarios but what this is really showing is an overall lifestyle people who have greater grip strength do a fair amount of physical AC AC it that by the nature of the activity engages and strengthens these muscles that contribute to grip they may do resistance training that requires the gripping and holding of weights or maybe they're very active with manual labor type activities out in their yard or using hand tools for home projects but the point is that these examples are showing physical activity that isn't just about grip strength alone it's not like people have good grip strength because they just sit withering away in a chair but hold on to some grip strength device in their hand while letting all their other muscles just shrivel away and die but as long as they keep gripping that grip device that they have they're going to have good outcomes for aging and Longevity no pretty much grip strength comes along with and is associated with all these other healthy activities and it's the totality of these healthy activities like resistance training and active lifestyle that have a more direct link to all these positive Health outcomes so for most people you probably don't need to go nuts on your grip strength especially if you do a fair amount of upper body resistance training that engages your hands and forearms it's one thing if you really enjoy something like rock climbing obviously you're going to be in the upper percentiles of grip strength if that is you but it still is probably worth throwing in a few grip related exercises into your routine which won't actually take that much time maybe at the end of a workout or somewhere between sets of a certain exercise you throw in some dead hangs with the goal of being able to hang with your body weight for 2 minutes straight which requires some good grip strength in order to do that or you could do modified farmer carries with dumbbells with the goal of holding the weights for 30 to 60 seconds or so and once you can hold for that amount of time you could increase the weight and you could incorporate these types of exercises a couple times a week so hopefully that helped to clarify how grip strength relates to health aging and Longevity and I hope you also learned some really cool Anatomy with those forearm muscles that we saw in the kadav sections one of the reasons I love the anatomy lab so much is that you do a lot of your learning by doing it's interactive it's Hands-On it's active learning and that's why I want to introduce you to another way to learn by doing and that's through saying thank you to the sponsor of today's video brilliant brilliant is an amazing interactive online learning platform with thousands of lessons in math science data analysis programming and even Ai and since I've been teaching Anatomy for the past 18 years I would often tell my students to try to minimize the blind memorization ask yourself and think about why was this anatomical structure given this name there was a logical reason for it and this is also what I love about brilliant brilliant helps you to build critical thinking skills through problem solving and again not just through blind memorization so while you're building real knowledge on specific topics you're also becoming a better thinker and currently one of my favorite brilliant lessons that's helping me to become a better thinker is 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