In last week’s post we talked about what/where the Scapulothoracic (scapulocostal) Joint is and more specifically how it moves. The big take away should have been that the ST joint is where the shoulder blade slides over the rib cage. It has this function so that we can position the shoulder blade and stabilize it so that the arm has a strong foundation to move from. In this post we’re going to be digging into the muscles responsible for these movements.

Before we do that, however, let’s talk about the basic set up. By now you’ve heard me say “it’s all connected” a billion times so it should come as no surprise that I’m going to say it again here. When it comes to the shoulder blade, there are layers of muscles pulling it in every direction. In this post, we’re going to focus on the big four that help stabilize the scapula and provide the postural stability we need for the arm to function. In this regard, the arms are no different than the legs. The muscles are connected fascially and function in chains. If part of the chain is pulled out of position or restricted in it’s mobility/strength, it will impact the rest of the chain.

For the scapula stabilizers, an easy way to visualize them is as a big “x”. These muscles work in two pairs and provide scapular movement in opposite directions. Imbalances in these pairs will result in one muscle getting pulled out of position, impacting both muscles in the pair and their ability to function. The first pair is made up of the rhomboids and serratus anterior (green arrows). The second pair is made up of the pec minor and lower trap (purple arrows).

Muscle pair one:

#1 Rhomboids

• The rhomboids lie between the spine and the shoulder blade. They originate along the spinous processes of vertebrae C7-T5 and attach to the medial border of the scapula (from the spine to the inferior angle).
• Technically there are two rhomboids on each side (the minor and major). Together these muscles work to retract (adduct/pull the shoulder blade in towards the spine, elevate and rotate the scapula down).
• The video below will go over how to find/palpate this muscle, as well as, how to stretch it.

#2 Serratus Anterior

• The serratus anterior is 100% an overlooked muscle. Think armpit muscle! It starts on the underside of the shoulder blade and then wraps around the rib cage in a fan like shape attaching to the first nine ribs.
• It is responsible for protracting the shoulder blade. It also helps with upward rotation, as well as, elevation and depression (the upper muscle fibers pull the scapula up and the lower muscle fibers pull it down).
• Another fun fact about the serratus is that restrictions in this muscle can make it difficult to retract the shoulder blade and open up the chest for a deep breath. Ever had a “side stitch” while running? This is the culprit behind it.
• The video below will go over how to find/palpate this muscle, as well as, how to stretch it.

Muscle pair two:

#1: Lower Trapezius

• The lower portion of the large trapezius muscle is part of the second stabilizing pair of muscles for the ST joint. You can see in the picture above just how big the Trapezius muscle is as a whole. The lower portion is what we’re focusing on here. These fibers attach from the spine of the scapula to the spinous processes of T4-T12.
• The lower trap helps position the shoulder blade by pulling it down (depression), rotating it upwards, and pulling it in towards the spine (retraction/adduction).
• The video below will go over how to find/palpate this muscle, as well as, how to stretch it.

#2 Pectoralis Minor

• Remember all of the times your parents yelled at you to stop slouching? 🙂 The Pec Minor is one of the muscles you are stiffening up by doing so. While the larger Pec Major gets more press, this little muscle underneath it can cause A LOT of problems when it gets stuck in a short position.
• The pec minor attaches to that little bony knob on the front of the scapula (the coracoid process), as well as, ribs 3-5. It’s responsible for pulling the scapula forward (abducting/protracting), rotating it down and depressing it. It also helps pull the ribs up to assist with breathing.
• The video below will go over how to find/palpate this muscle, as well as, how to stretch it.

Video: How to find and stretch these muscles

Click here to return to part one: Intro to the ST joint

Click here to continue to part three (coming soon)

To kick off our shoulder series we’re going to be talking about the scapulothoracic joint (ST joint). Some of you may also know this joint as the scapulocostal joint. Either way, we are talking about where the shoulder blade (purple in the picture above) connects and moves over the underlying ribcage (red). The reason I want to start off our shoulder series here is that this piece of the puzzle is often overlooked by athletes. While it’s easy to focus on the shoulder joint as the source of your injury, the first part of the evaluation should always be to look at the shoulder blade and how it moves.

The reason for looking at the ST joint is simple: it’s sole purpose is to help position the shoulder blade so that the head of the humerus remains in full contact for maximum stability and efficiency. Let’s look at the picture below to show you what I mean:

The groove in the scapula where the humerus attaches is called the glenoid fossa. It’s the purple part of the picture above (where the humerus has been removed). This groove is curved so that it is a ball and socket joint. The “ball” of the humerus (aka the humeral head) is then able to move in that groove, giving you all of the different movements you see at the shoulder.

The ST joint functions to position the glenoid for optimal contact between the humeral head and the scapula. It does this through muscles that are able to pull the shoulder blade in different directions. These directions include:

• up (elevation)
• down (depression)
• in towards the spine (adduction/retraction)
• out away from the spine (abduction/protraction)
• upward rotation (meaning the most lateral tip rotates up)
• downward rotation (meaning the most lateral tip rotates down)

Now these movements may not seem that important by themselves, but they are hugely important when you think about the impact they have on the shoulder joint itself (glenohumeral joint). If your shoulder blade gets stuck and becomes unable to move, the arm will be forced to pick up the slack. The real problem with this is that the glenoid we’ve been talking about will be out of position and the bigger stabilizing muslces will be unable to maintain full contact with the humeral head. This is the start of impingement syndromes! If that continues, the humeral head can start pinching and fraying rotator cuff tendons and the bursa. It can also cause increased bone to bone contact which is always good for creating bone spurs and can even tear the cartilage/labrum.

Bottom line: healthy, mobile joints have SPACE. Tight, unstable joints do not. So if you’re someone who’s been diagnosed with spurs or has a rotator cuff tear or just has pain anytime you work with your arms overhead, you should be working to restore that space!

Just like we did with the foot, we’re going to be working our way through the different layers of muscles. This means we’ll talk about how to evaluate these areas and what to do for them self treatment wise.

Continue to part two (coming soon)

Let’s face it. As endurance athletes, our injuries are rarely traumatic. They gradually and slowly build over time. Sure they may “sneak up” on us when they do strike, but the bad mechanics and mobility restrictions that led to them have been long time training partners by then. The shoulder is another perfect example of this.

Just like the foot and ankle, the shoulder is a complex region that functions through the coordinated movements of multiple joints and layers of overlapping and intersecting muscles. That means LOTS of potential areas for problems to start and even more potential for us to develop horrible compensation habits to work around those problems.

First, let’s talk about the shoulder girdle itself (below). There are three bones (four technically if you count the ribcage).

• Clavicle/collarbone. This is in blue.
• Scapula/shoulder blade. This is in green.
• Humerus/upper arm bone. This is in red.
• Ribcage. I’m going to include this here as it is part of one of the four joints we’re going to discuss.

(before I forget, skeleton provided by Visible Body’s amazing skeleton app. Color and drawing over it is all me. 🙂 )

Now that we know the bones involved, let’s talk about the joints they create. Moving the arm and shoulder requires the coordinated and balanced effort of four separate joints. This means that each of those joints is rotating, gliding, and getting into position so that you can move your arm in an efficient and powerful way. When those joints get pulled out of position or mobility/strength restrictions prevent them from doing their job, injuries aren’t far behind. This is where you see things like impingement, bursitis, tendonitis, and gradual tears of the rotator cuff and joint cartilage. Like we’ve said all along, a healthy and happy joint is one that is stable and mobile.

In the picture above you will see the four joints that make up the “should girdle”:

• Glenohumeral joint (GH)
  • Let’s start with the one that everyone already knows. This is where the humerus (red) attaches to the scapula (green). It can move in six directions: flexion, extension, adduction, abduction, external rotation and internal rotation.
• Scapulothoracic joint (ST)
  • While the GH joint gets top billing, this joint is equally important. There is no bone to bone attachment here though. This joint is a functional one as it is stabilized/held together by muscle instead of ligaments and a joint capsule. That means that the scapula (green) is held against the ribcage by muscles attaching to both. An easier way to look at it is this- the scapulothoracic joint is what positions the bony socket that the humerus fits into (aka the glenoid fossa). It can move in six different directions including: elevation, depression, abduction (protraction), adduction (retraction), upward rotation and downward rotation.
• AC (acromioclavicular) joint (AC)
  • The name of this joint may sound familiar so here’s a hint if you can’t quite place it- this is the joint that gets damaged when someone “separates their shoulder”. While the humerus attaches to the scapula in the GH joint, the scapula also attaches to the clavicle (collar bone) at the AC joint. This joint is primarily responsible for positioning the scapula and the glenoid fossa so that the humerus can stay in contact as the arm moves. It does this by gliding forward and back, as well as, up and down.
• SC (sternoclavicular) joint (SC)
  • Lastly we have the SC joint. This is the only true bony attachment to the skeleton at the sternum. Being a small joint, it should make sense why the shoulder is known as the least stable joint in the body. Like the AC joint, the SC joint is responsible for getting things into position for the large GH joint to function properly. To do so it can move in three directions: elevation/depression, protraction/retraction, and rotation.

In this upcoming series we’re going to start digging into each of those joints and all of the muscles responsible for moving them. We’re also going to talk about treatment to decrease impingement (when joint spaces are lost and tendons, bones, etc get pinched and inflamed). Lastly, we’re going to talk about how imbalances here can set you up for neck, elbow and hand problems.

Sound good? This series kicks off next week. Hope you’ll join us.