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  • Writer's pictureMia

What the hell do shoulders do? Part three.

try not to laugh at this gif

We're diving into the musculature of the shoulder, after taking a look here and a look here at the shoulder joints themselves.

Don't skip these blogs about bones just because muscles are sexier! Muscles don't make any sense unless you know what they're pulling on. Getting a stronger muscle suit works best when you know what's happening underneath your muscle suit. You think Christian Siriano designed this dress for Billy Porter just by sewing some pieces of fabric together? Hell no.

The attention to detail is astounding. Couture designers who sew everything by hand have a stitch-by-stitch understanding of fabric. How Billy's hem will fall as he walks, for example, or how adding a silk organza lining inside his jacket (which no one will ever see) will add structure to the outside of his jacket. Your skeleton is the silk organza lining. This knowledge of the literal underpinnings is what makes the difference between something you feel absolutely great wearing, and something you have to tug on, shift, and feel self-conscious in all night.

Same with muscles. You want muscles that are pulled and supported by perfectly-stitched bones, so that from the outside your movement looks utterly effortless. If every time you try to do a shoulder press or a pullup and you find yourself constantly shifting one hand around to find the "right" position, that's just like pulling and tugging on a shirt to keep it in the right place. It's not the fabric, it's the stitching.

Taking the time to understand the bone mechanics is worth it, and god knows a lot of us have got time right now, so don't skip it. But if you're good on bones, let's get up close and personal with the shoulder muscles that move them.

The Baldwin Muscles

The main shoulder movers are some of the biggest muscles in your body. The latissimus dorsi (lats, your mid-to-lower back), the deltoids (delts, your big shoulder caps), the trapezius (traps, the triangular upper back muscle), and the pectoralis major (pecs, your big chest muscles).

I've framed each muscle as if they were one of the Baldwin brothers. Gotta do something fun in quarantine.

Billy Baldwin: The Lats

Like Billy, the lats are pretty good on their own, but are made way better by what they're attached to. Billy did Backdraft, which was awesome, but then also married Chynna Phillips, of the epic group Wilson Phillips. You see what I mean by great attachments?

Similarly, the lats are themselves an inferno of flamepower, but they also have some attachment sites of red-hot importance. Your lats attach straight from your lower back and hip bone all the way up to the inside of your arm bone. This means that working on your lats in any way can have direct impact on both low back pain and chronic shoulder pain. (All of the anatomy pics come from Essential Anatomy, the app I can't live without.)

Look at this giant wing you have!

The lat in isolation

On the way across your body, your lats can attach to all kinds of things. Anywhere from six to twelve vertebrae, both directly and indirectly. They can attach to three or four ribs along the way, or not. In most people, they attach to the bottom tip of the shoulder blade, but in some people they don't. For others, the lats merge with some of their bicep / tricep / a whole bunch of the other local muscles, including your chest. Some lats don't merge at all. Bodies are weird. This young kid's lat is perfectly outlined for us to see how they work in real life.

Better than anatomy books!

In terms of function, the lat slays. From pulling down from overhead (decelerating that heavy bag from the overhead compartment), to pulling horizontally (grabbing your loved one for a dramatic movie kiss), to internal rotation of the arm (teach me how to dougie), sideways flexion of the trunk (think the movement that shitty women's magazines like to advertise as getting rid of muffin tops), rounding AND arching the spine, tilting the pelvis (hellooooo, john travolta), AND helping you breathe. As my mother would say when a customer was really pissing her off, "What more may I do for you, ma'am?"


Healthy shoulder muscles are meant to pull from every direction.


Even cooler, your lat is so fucking strong as an internal rotator that it can cause shoulder dislocations in people who have been electrocuted. (I'd be so pissed if I got electrocuted and then dislocated my shoulder on top of it. Although what your muscles can do when they get shocked is incredible. Note to reader: in general, for good health, try not to get electrocuted.)

Considering how major a role your lats play in your life, they get wholly ignored by a whollot of people. A bunch of chronic pain can be probably be relieved just by adding regular pulling movements into your life.


The lats are quieter, like Billy, and have an unfortunate family association (the traps), which allows them to be regularly overlooked. But Billy isn't his family. He did Backdraft, Forgetting Sarah Marshall, and he got married and stayed married (!). Don't let your bitchy traps rule the back muscle roost. You need lotsa lats. Things that help your lats retain their length and elasticity are hanging from things, pressing things overhead, and pulling things from overhead.

Daniel Baldwin: The Delts

The delts are named for the Greek letter delta, which is a big ol' triangle and your delts are, in fact, a big ol' triangle on top of your shoulder.

Just like cap sleeves!

Daniel Baldwin is a puffy douche, and so are your delts. Absolutely they are strong primary movers, and they play a vital role in both lifting your shoulder and preventing it from dislocating downwards when you're carrying something heavy (which is, uh, important). Of course, like all the Baldwins, they overestimate their own importance. Your deltoids are strongest when they are lifting your arm straight out to the side. But if you had a paralyzed deltoid, your supraspinatus (one of your rotator cuff muscles) could also manage this task, so, you know, stop thinking you're the whole center of the world, Danny Deltoid. (In fairness, your shoulder would be really weak.)

Also like Daniel, who has seen the inside of movie sets, reality tv houses, and a whole bunch of jail cells, the deltoids do a little bit of everything. Rather than just one primary movement, your delts help you lift your arm to the side, front, back, and assist with both internal and external rotation.

The delts are one of those muscles you can see in a mirror and they make sense. If you put a weight overhead, you can see your shoulder lifting the weight. This influences people to do tons of shoulder presses and lifts, which is great for overhead strength and range of motion work...and not so great for your AC joints (which get smushed every time you shove your arms upwards) and your rear rotator cuff (which desperately pulls in the opposite direction to keep your arm bone centered in the socket). Delts are sexy for sure, but they're only as sexy as the tendinous junctions beneath them. No one else will ever call your tendons sexy but I will, because I'm fun at parties. Is that some taut dense connective tissue or are you just happy to see me?


We all remember how Daniel Baldwin was immediately voted off all of his five (5) reality shows owing to his exceptionally loud voice, unbearable ego, and refusal to show up on set. Deltoids are easy to train and easy to gain, but they primarily do what they like best, which is to pull aggressively upwards. Don't vote them off the island. Instead, learn to understand them better. Ways to counter this upward pull include overhead downward pulling, specific rotator cuff strengthening, and exercises for your lower traps.

Stephen Baldwin: The Traps

Whew. Stephen is fucking needy. Cannot take any personal responsibility for his actions. Evades taxes, did a lot of drugs, and became a born-again Christian which is suspect in any situation but it's REALLY suspect when you do it because of the 9/11 attacks. He's got a Hannah Montana tattoo, which he got when he was 42 years old. Stephen--and your traps--are kind of fucked up dudes.

Traps run from the base of your skull all the way down to the bottom of your thoracic spine, which is nineteen vertebrae away. They stretch across your back like a fabulous muscle cape and attach to your collarbone, the top of your shoulder blade, and the back of your shoulder blade. Between your traps and your lats-- just two muscles--you're covered from skull to hips to shoulders and all the way onto your arms. That is a ton of real estate for improving movement and pain.

Traps are one of the major shoulder blade movers. The traps move your shoulder blade upwards towards your ears, backwards (as in pinching your shoulder blades together), and downwards, as well as helping to stabilize the shoulder blade rotation that happens when you lift your arm. And because they just wanna do it all and get credit for it, they can also extend your neck, as when you're rolling your eyes in exasperation.

Now, the traps, like Stephen, make a lot of bad errors in judgment. We spend a lot of time with our arms doing something somewhere in between rib cage level (like carrying a pot) and slightly above the shoulders (like putting bowls away in the cabinet). This makes high use of the upper traps, and far less use of the middle traps and lower traps. A body which isn't making full use of the middle and lower traps will default to trying to get everything done with the upper traps, even when it's not appropriate. This leads to the famous "stop shrugging" directive that every personal trainer, strength and conditioning coach, and physical therapist on the planet has yelled at someone.

Stephen has been in an ungodly number of reality tv shows, from surviving Omarosa's season of The Celebrity Apprentice to breaking his shoulder blade on Ty Murray's Celebrity Bull Riding Challenge. (Of the two, breaking his shoulder was probably way more fun.) Someone needs to be like: Stephen! Dude! You can make money other ways besides the next season of celebrity dog grooming.

Same with your traps. The upper traps serve an important function (they hold your shoulder blade at the most ideal angle, among other things), but they don't have to say yes to every pullup, pushup, shoulder press, and bicep curl offer that comes along. If yours are doing this, it's time to let the middle and lower traps participate in the fun.


Just like we don't want Stephen Baldwin founding any more ministries, we don't want the traps constantly yanking up on the collarbone and shoulder blade. We want them to find other interests, like relaxing, taking a load off, and letting someone more qualified do the work instead. That would be your lats, rotators, triceps, serratus anterior, and rhomboids.

The Pecs: Alec Baldwin

Your other big gun shoulder muscles are celebrities for sure, but they all wish they were the pecs. Everyone wants to be Alec.

Alec is the oldest Baldwin, the richest Baldwin, the most famous Baldwin, the Baldwin everyone forgives for acting like an asshole because he's a funny asshole. Alec is the pecs. He acts like a jerk in a way that looks great in t-shirts. If you put your hand over your heart, you're roughly outlining the pec major. There is also a pec minor, which is a much smaller but generally more troublesome muscle. The major is like how Alec can donate $15 million to charity and then the minor is when he calls his eleven year old daughter a thoughtless little pig. Complicated creature, Alec.

There's something about the pecs that automatically adds an asshole quotient whenever you talk about them. I once trained a real douchebag dude who would do pushups and then stand up and be like "What's this for, my tits?" with a big stupid grin on his face. He made that joke a thousand times. A. Thousand. Times. This dude was super successful and it was like training Beavis and Butthead.

The pecs start from your sternum and your collarbone and attach near the top of the arm bone. They play a big role in keeping your arm attached to your body. Utmost respect for things that keep our limbs firmly attached. They're also the primary mover of the bench press and the pushup and are surprisingly involved in pulling as well. You'll meet plenty of people who still believe in the whole "pushing" and "pulling" workouts, where they think the chest muscles and back muscles are separate entities. They're really not separate. Go ahead and get your pecs good and sore, and then try some pullups. You'll feel it.


It's not the fabric, it's the stitching.


Pec major is usually a pretty cool dude, very Jack Donaghy. Macho, capitalist, handsome. It's the pec minor that rears up unexpectedly, just like all those AlecAssaults™ in parking lots, airplanes, and random NYC streest. Hate when I abuse every flight attendant who asks me to turn off my phone.

Pec minor runs underneath the pec major, but it's angled upwards and attaches to your shoulder blade. Because of this, it often functions as an over-aggressive shoulder blade puller, when the back of the shoulder isn't strong enough or well-trained enough to perform that role.

Your pec minor, in wanting to add some support to a "loose" shoulder blade, can pull your shoulder into a rounded shoulder posture and hold it there. This sucks for posture, but also can grind your arm bone into the socket when you reach overhead. Plus, pec minor is an important breathing muscle. Tight pec minor + rounded shoulders + harder to breathe...this is not how you want your chest to be living.

Oof, look at that forward pull


Are you sensing a trend? These big muscles that surround the shoulder are responsible for pulling hard on your arm. It's a good thing; we like our arms to sit firmly in their sockets. But it also means that training the entire shoulder blade support team (rotator cuff, rhomboids, mid/lower traps, serratus anterior) is vital for both athletes and non-athletes alike. You can start loosening your pec minor just by taking several deep breaths, focusing on the exhalation.

In a healthy shoulder, this is how the muscles should be behaving: (Arrows are showing the lines of pull that each muscle is creating.)

Healthy shoulder muscles are meant to pull from every direction as you move. This is where stability and strength come from. (The final part of the circle is serratus anterior which pulls from back to front, I just don't have a good side picture to use. You'll meet SA in the next part, but it's the fanned ribcage muscle you see in the opening gif to this blog.) This multi-directional pull not only keeps the arm bone properly placed in the socket, but also helps prevent overuse on one side owing to underuse on another side.

The more you understand what your shoulders are doing, the stronger you can get in the long term. Video from behind is ultra helpful. Try videoing an overhead press, a pullup, and a pushup. (It will be even more telling if you do it when your arms are tired, like at the end of a workout.) In healthy shoulders, you'll be able to see muscles pulling in all directions and shoulder blades rotating cleanly. In an unhealthy shoulder, it might shrug hard, move more slowly than the other, look stuck, rotate poorly, or wing backwards. I just caught my own shoulder winging the other day when I did a postural video check for this blog series.

This video was intended to show both scaps pressing straight downwards. What the fuck is that right shoulder doing? You trying to be a Baldwin too? That shoulder blade winging is probably some combination of serratus anterior taking a snooze and lower traps putting up a huge middle finger.

Next installment: The forgotten muscle: Serratus anterior, plus the mfing rotator cuff.

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