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Fixing (or preventing) Scapular winging

A sequence of muscle activations for stabilizing the shoulder blade relative to the ribcage

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Muscles that can prevent scapular winging. Using serratus anterior to protract, lower trapezius to rotate inner border of shoulder blades downwards, external rotators to resist latissimus dorsai which in turn work against serratus anterior. Neil Keleher, Sensational Yoga Poses.

At the time of initial writing, I understood that the muscles important in the prevention of scapular winging (winging shoulder blades) are the serratus anterior, lower trapezius, the teres major and/or the latissimus dorsai. Luckily, this article sat for a while before publishing it, and in the interim I discovered a little bit more about preventing scapular winging.

A week triceps, symptom or cause or scapular winging

My left arm has been consistently week in triceps push downs, standing triceps extensions and dumbell military press. My left triceps long head has been underdeveloped for as long as I can remember. And recently, over the last few months, perhaps longer, I've had a lot of difficulty getting my serratus anterior on that side to activate.

The upper serratus anterior and pushing against the resistance of the collar bone

Part of the problem may have been that my upper serratus anterior wasn't activating. This is the portion that attaches to the upper portion of the inner edge of the shoulder blade (where the inner edge angles inwards, just above the line of the scapular ridge) and from there to the first (and perhaps second) ribs.

This portion of the serratus anterior is important because it pushes almost directly against the leverage of the collar bone. And so one of my exercises in getting this portion of the serratus to activate was to focus on feeling the collar bones while I'm protracting the scapula.

An alternate mechanism for creating protraction

With a lack of serratus anterior activation what I may have been getting is a slight lifting action, possible the mid trapezius activating to pull the accromion process forwards. As a side note I think at the time I may have had trouble with the subclavius not activating. Note that I was getting a protraction, it's just that it wasn't the serratus anterior that was driving the action.

As a note here, fibers of the upper trapezius ride over the bulk provided by fibers of the middle trapezius. The activation of the mid trapezius may act as a fulcrum for the upper fibers. And that may in part be how "protraction" is created without the (full) use of the serratus anterior.

As a side note, it is easy to protract the shoulder blades by using the pectoralis major. However, I'd suggest here that walking around with pecs continuously activated is not an optimum solution for fixing scapular winging.

As with a lot of body explorations, getting the upper serratus to work was only a partial solution.

Getting the lower trapezius in on the act

As mentioned, the upper serratus anterior attaches near the top inner corner of the shoulder blade. Another muscle that attaches near this point is the lower trapezius.

The lower fibers of the trapezius attach to a tubercle along the scapular ridge, the ridge that crosses the back of the shoulder blade. This tubercle is reasonably close enough to the upper inner corner of the shoulder blade to suggest that the fibers of the lower trapezius and those of the upper serratus anterior can work together.

Activating the upper serratus gives the lower trapezius a force to act against in order to pull down on the inner border of the shoulder blade.

Sequencing serratus anterior and lower trapezius activation

In my experience so far it makes sense that the sequence of muscle activations is as follows.

The initial stages of protraction may lack shoulder blade rotation, but as it progresses, the upper portion of the shoulder blade meets resistance from the collar bone.

Protraction of the upper portion is reduced the more the shoulder blade is protracted. However protraction of the lower portion is not reduced. This results in the lower part of the shoulder blade protracting more than the upper part. The bottom tip rotates outwards, or, if you like, the inner border rotates downwards.

This is where the lower trapezius comes in. It helps rotated protraction when the shoulder blade comes up against the collar bone by pulling down on the inner edge of the shoulder blade which causes the bottom tip to move outwards.

So in my exploration of left shoulder protraction my next step was to focus on lower trap activation. This was succesful to a degree, but it still seemed like there was another part to my shoulder puzzle.

The middle fibers of the trapezius

Addendum: also important here is the mid traps. It aids in rotation by pulling inwards on the accromion process. I'd suggest here that the most important portion of the serratus is the upper portion, and so for all three of these muscle segments, the scapular ridge might be the ideal reference (and this includes the accromion process), as well as the medial border of the scapula.

The steps for including middle trapezius activation might be to focus on moving the accromion process forwards during initial protraction, then pull it back while keeping the protraction.

Muscle activation requires an opposing force

In any scenario, for a muscle to activate it has to be working against an opposing force. Muscle activation produces force which tries to create movement. A muscle won't activate in the absence of an opposing force. It can be opposed or resisted by an opposing muscle, or by working against an outside object or by working against some portion of the body and the weight of that body part.

Activating the serratus anterior and lower trapezius against the weight of the arm

In the case of protraction the serratus anterior muscles are working against the weight of the arm.

As the shoulder blades are protracted, they tend to ride over the top of the ribcage. In an upright position the serratus helps to pull the shoulder blades up and over the ribcage.

In the case of pulling the inner edge of the shoulder blade downwards, the shoulder blade pivots over the ribcage where it connects to the collar bone, at the accromion process. Since the shoulder socket is on the other side of this pivot point, the lower traps work against the weight of the arm.

Unless the muscles of the shoulder are completely relaxed, it may be challenging to get pure serratus and lower trap activation. And this was the problem that I was having.

Because other muscles were activating to help carry the weight of the arm, my serratus anterior and lower trapezius were having difficulty activating because they had no opposing force to work against.

Teres major and latissimus dorsai

To get the necessary awareness so that I could optionally choose to relax my shoulders while protracting if I chose to I had to learn to activate the teres major and lattisimus dorsai.

Both of these muscles attach to the front of the humerus, just below the top of the humeral shaft.

Teres major

The teres major attaches from there to the bottom of the outer edge of the shoulder blade, near the bottom tip. Working from the arm, this muscle, like the lower trap, could be used to help pull the bottom tip of the shoulder blade outwards.

Latissimus dorsai

The upper few fibers of the latissimus dorsai cross the bottom tip of the shoulder blade to attach to the spine. From there the remaining fibers attach to lower and lower segments of the spinal vertebrae, the upper rear crests of the pelvis and the sacrum and to fibers from the opposite side gluteus maximus.

Both these muscles can work to internally rotate the upper arm or to help resist external rotation.

Shoulder muscles that create external arm rotation

Muscles that externally rotate the shoulder include the infraspinatus, attaching just below the ridge of the shoulder blade, and the teres minor, attaching to the outer edge of the shoulder blade, above the teres major.

Both of these muscles attach to the back of the upper arm bone, at or just below the top of the humeral shaft.

Stabilizing the shoulders and shoulder blades

In order to stabilize the shoulders and the shoulder blades, the external rotators can work against the internal rotators.

Bear in mind that not only do the upper portion of the latissimus dorsai act to internally rotate the upper arm, they also act to pull the arm and shoulder blade inwards. And the lower fibers act to create a downwards pull on the upper arm bone.

The lat then potentially works against both the serratus anterior (which pushes outwards) and the lower trapezius (which pulls downards on the inner edge of the shoulder blade).

And for this reason, the latissimus dorsai may be the final piece in the puzzle for effective protracting and anti-winging of the shoulder blades.

Obviously, the external rotators are also important in that they resist the internal rotation of the latissimus dorsai. However, if protraction is created with the intent of keeping the upper arms rotationally stable these muscles should automatically activate.

So why the weak triceps?

Now I have yet to try my left sided dumbell presses and triceps extensions, but the theory here would be that the long head of the triceps needs a stable platform from which to activate, particularly against heavier weight.

I was reaching a thresh-hold weight above which my right arm felt fine but my left arm felt as weak as tea made from a tea bag which had already been seeped two or three times.

The long head of the triceps

In a standing pulley triceps extension with the upper arm down by the side with the idea to work against a pulley to straighten the arm, protraction with both serratus and lower trap activation would push the shoulder socket forwards and resist it being pulled downwards.

The long head of the triceps attaches to the outer edge of the shoulder blade just below the shoulder socket and so this could be advantageous for effective triceps activation. The long head triceps may try to externally rotate the upper arm and so here lat and teres major activation may be important to resist that external rotation tendency, as minimal as it may be.


I haven't mentioned the subscapularis, which also acts to internally rotate the shoulder. If there are further problems later on down the road then this would be another place to look.

Working with the arm above the head

In an arm above the head triceps extension (using a dumbell) the weight of the arm creates a downward push on the shoulder socket (as it would with the arm down).

So that the upper arm can clear the accromion process, the scapular rotation created by the lower trap is even more important. But in addition the mid trap is also active in order to crate an upward pull on the outer edge of the shoulder blade.

The middle fibers of the trapezius attach from the accromion process to the cervical vertebrae and so pulls both inwards and upwards on this portion of the shoulder blade helping to pull it out of the way of the upper arm when it is lifted.

Protraction is also important here since the more the shoulder blade is protracted, the more the shoulder blade rotates.

Here the lat may be important in that it creates a downward pull on the upper arm. The shoulder joint capsule itself may be strengthened by added tension created by the twisting of the upper arm relative to the shoulder.

So several possible approaches to fixing the triceps in this position can include pulling inwards on the accromion process for better mid trap activation, pulling downwards on the inner edge for lower trap activation, protraction for even more rotation and for serratus anterior activation to help resist the inward pull of the the upper portion of the lat. Lower lat activation could be caused by creating a downward pull on the upper arm.

Why bother with arm over the head work if the problem is with scapular winging?

One reason for potentially playing with arm over the head work when dealing with scapular winging is to help figure out the root cause of scapular winging. This only applies if you have in-balanced scapular winging, i.e. one scapulae wings and the other doesn't. But even if you have "balanced" scapular winging, these exercises could be used as a test of shoulder function or failing that, simply a way to see if you can use muscle control to improve your strength in these exercises.

Anchoring the lower trapezius

One final note (and this is added after this article had been sitting in limbo for quite some time) is related to the lower fibres of the trapezius. How do you anchor them so that they can work to pull down on the inner border of the shoulder blade?

These fibers of the trapezius are normally described as attaching to the spine (or at least that's been my assumption). And to be more specific, they attach to the spinous processes. To anchor these fibers, it helps if there is a downwards pull on the spinous processes. Generally that means having some sort of spinal erector activation.

One of my more recently discovered problems has been a lack of spinal erector activation on the left side. I started playing with the spinal erectors that attach to the ribs (longissimus and iliocostalis) and found that not only did that help my general posture, it also seemed to help shoulder stability. And so a suggested step if you have un-balanced scapular winging, is to check that you have balanced erector spinae activation.

Simple exercises that may help with scapular winging

Since a large part of preventing scapular winging can include learning to control the shoulder rotators, one way to work on it is with some shoulder rotation exercises as show here: shoulder rotation exercises.

Published: 2020 08 05
Clearly defined poses, exercises and stretches for improving stability, body awareness and flexibility.
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