Yoga Anatomy Lab: The Lats

we'll start our discussion with the muscles that move the arms with the latissimus dorsi we'll refer to it as the lats from here on out so this is a massive muscle whose origin covers kind of a lot of terrain here on the posterior side of the body its origin is at the spinous process of the thoracic so t7 all the way down to l5 so it crosses half of about half of the thoracic all the way down the lumbar spine its origin is also at the iliac crest the inferior ribs and the inferior angle of the scapula so it's this massive kind of sheet of muscle that's just its origin it inserts into the bicipital groove and not quite at the humeral head but just below it here at the humerus bone so it kind of goes through to the side and inserts here at the front so this muscle you can kind of touch or palpate it just underneath your armpit it's it's this muscle here that you can kind of grab onto now as it goes deeper and inserts into the humerus bone you really wouldn't be able to feel it and the muscle certainly gets a lot thinner as it kind of crosses more of the back here but it's a nice place for you to feel it if you kind of reach your arm forward and and plug your arm bone back you can kind of grab hold of that muscle and it's also nice to see how it affects the upward rotation of your arms so if we've got its insertion here and its origin back here and we were to bring these together to contract or to strengthen or them let's think of some of the directions that might pull the humerus bone so it will pull it into extension and it's a big mover when we think of the arm being over the head being able to draw the arm down and extend it behind you you're using your lats when you do that so if its insertion is here and its origin is on the posterior side and and it contracts and draws it together you can imagine that it would add duct to the arm and because it inserts at the front of the humerus we could also imagine these two points here the inferior angle of the scapula and the humerus bone if those were to contract it would internally rotate that humerus bone so it does quite a lot of things there so we can see as it it's pulling the arm bone down and going to extend it behind you it draws the head of the humerus bone into the socket there now this is the only muscle that goes from the arm bone to the pelvis so in that way you can think of it coordinating a lot of our movements let's think of some postures where we might really use this the lats so upward facing dog we could think of now i know it can get confusing with the arm bones i would never like cue to internally rotate your upper arm bones because i feel like i would get a lot of this from students but in fact there's a slight internal rotation in order to kind of neutralize the arm bone similar to how we might suggest the same in pashimo tanasana even though the legs are straight and we're not asking for this deep internal rotation the thigh bones the femur bone slightly internally rotate there to kind of neutralize the thigh bone and the hip socket so it's very similar with that an upward facing dog so we've got a slight internal rotation of the humerus bone we've got the arms adducting together now even though we're not extending the arms behind us an upward facing dog there's this action of pushing down through the hands and pulling the chest through so there's a isometric contraction there of the latissimus dorsi so also those rhomboids are working to retract the shoulder blades but this is a great posture where we've got kind of all three of those actions happening so the lats are really helping facilitate this kind of pulling through of the chest another great way to show the latissimus dorsi working is thinking through the transition of downward facing dog to plank so i talked earlier about how the latissimus dorsi really work when the arms are over the head and they're working to bring the arm back into extension so if we think of downward facing dog arms over the head and what's that transition we do so often going into plank pose so pulling the arms into extension and then the lats are there to help kind of draw the head of the humerus bone into the shoulder socket so that's another great example reverse table top is another good one so you know working the back body to push and lift the chest up as the arms are extended behind us and again we don't want this internal rotation but as we go down there's a slight drawing in adducting a slight internal rotation to kind of neutralize those arm bones again not to be confused with this now in terms of stretching this massive muscle remember we've got this massive origin if we lift the arm over the head and take a side bend we're getting into a nice part of the origin here the insertion remember up here at the humerus bone we're getting a nice stretch of the lats so your reverse warrior or any pose you want to take adding in a side bend or even just standing side bend it's going to get into those lats puppy stretch is another great pose because remember if if the lats primary roll or one of them is to extend the arm behind then if we flex the arm in front of us that's going to do the opposite action plus we have that nice pressure so that's going to stretch the lats now the lats and the triceps which we'll talk about later also kind of get all slightly involved with each other so if we were to bend the arms we'd be stretching the triceps and the lats there in our puppy stretch so sometimes adding in those different variations to kind of really articulate what you're stretching can be useful