[Music] don't you worry just keep watching this video and you'll know the lumbar plexus in no time and stick around for this mnemonic i twice get laid on fridays and also i'll share this super special trick we can't do these videos without you if you hit the subscribe button we'll make sure to do a lot more of these helpful lessons okay let's do this lumbar plexus is formed from the anterior rami of the lumbar nerves l1 to l4 and also receives some fibers from the thoracic nerve t12 let's look at the anterior view of this area we'll first label the medial side and the lateral side now let's label some bones and helpful landmarks vertebrae l1 l2 l3 l4 and l5 this is the sacrum the pelvis the iliac crest the iliac fossa the obturator for ramen the pubis symphysis and the inguinal ligament here and let's not forget the femur bone next we'll label some nerves that we'll cover in the next lesson here's the lumbosacral trunk the sciatic nerve and the sacral plexus in this lesson we'll learn the six main nerves that come off the lumbar plexus this lumbar plexus actually forms inside the psoas major muscle which we have shown here and the branches of the lumbar plexus can be understood in relation to the psoas major muscle and where they emerge from this muscle okay first a high yield must know fact is that all the nerves emerge lateral to the psoas major muscle except the genital femoral and the obturator the genital femoral nerve l1 and l2 actually emerges anteriorly from the psoas major muscle and the obturator nerve l2 l3 and l4 emerges immediately from the soil's major muscle the rest emerge lateral to the psoas major muscle so the laterally emerging nerves are ileohypogastric l1 ilioinguino l1 lateral femoral cutaneous l2 and l3 and the femoral l2 l3 and l4 so now you know the relationship of where the nerves of the lumbar plexus emerge from in relation to the source major muscle let's now use a mnemonic to never forget them here we have taken the lumbar plexus in all its glory we'll label the nerve roots here in yellow beginning with l1 l2 l3 l4 and l5 the nerves you're seeing in blue are the anterior divisions of the lumbar plexus and in pink are the posterior divisions now don't be afraid we got this to learn this we'll use the mnemonic i twice get laid on fridays i hope this is true for some of you also let's write down this super cool trick over here because we'll use this to remember the nerve roots two from one two from two and two from 3. i'll show you this in a bit the mnemonic reads i twice for the iliohypogastric and the ilioinguinal nerves i comes twice the iliohypogastric is superior and the ilio inguinal is inferior you'll remember this for sure because you know gastric from that iliohypogastric has a stomachy ring to it and the stomach is definitely superior to the inguinal region now we'll use this key you see it says two from one this is because two nerves come from one root value l1 iliohypogastric and ilioinguinal are two nerves from one root value l1 i twice get laid okay easy now get is the genital femoral nerve from l1 and l2 and laid has to come after the genital right so laid is the lateral femoral cutaneous nerve of the thigh this nerve comes from root values l2 and l3 now you see the genital femoral nerve l1 and l2 and the lateral femoral cutaneous nerve l2 and l3 both of these two nerves come from two nerve roots so use this key two from two next to the mnemonic is i twice get laid on friday yeah both of them are pretty heavy laying on me and yes these two nerves are pretty large nerves that innervate the largest muscle groups on is for the obturator nerve and the friday is for the femoral nerve operator nerve innervates the muscles in the medial compartment of the thigh and the femoral nerve innervates the interior compartment of the dye now these two nerves have the largest number of nerve roots we use our trick two from three two large nerves from three root values as you can see both of these nerves have the same root values l2 l3 and l4 awesome now let's quickly review first we must know that the lumbar plexus is coming off the anterior ramis of l1 to l4 second we must know as the mnemonic i twice get laid on fridays this gives us the order of the branches of the lumbar plexus now our last thing we must know is the trick two from one two from two and two from three that twice getting laid will make you remember this trick and you'll quickly write down two two two and then just one two three on the right now putting it together we know now that i twice iliohypogastric and ilioinguinal nerves are the first nerves in order and are two nerves from one root value l1 next we get laid is the genital femoral a1 and l2 and the lateral femoral cutaneous l2 and l3 and these two nerves are from two nerve root values each lastly we say on fridays which is the largest amount of nerve roots two nerves from three roots the operator nerve with these three roots l2 l3 and l4 and the femoral nerve originating from the same three nerve roots l2 l3 and l4 great job that's all now adjust some nerves for completeness sake up here there is a subcostal nerve from the last thoracic nerve the 12 thoracic nerve which contributes to the lumbar plexus here from the third and the fourth lumbar nerve roots is the accessory operator nerve which isn't always there lastly the nerves here are just muscular branches to the psoas and the iliacus muscles well done and awesome for staying with us don't forget to re-watch this video and have some paper and markers nearby draw it over and over and practice recalling the structures if you'd like to see more of this lesson head over to our instagram page and tick tock channel at rev.med we'll have this lesson along with many other topics for you to study by the way don't forget to do questions are you learning something from our videos well then click the subscribe button to your right we are releasing high yield lessons and ways for you to get 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