The Right BC Pattern
The Right BC pattern is a position of torso counter-rotation to the left in response to the Left AIC pattern that results in a pelvis that is oriented to the right.
If you stand up and push your left hip forward, you’ll notice that your entire torso orients to the right. You are not oriented straight ahead.
To correct this issue, your torso, from about T8 up, via the right brachial chain muscles, rotates back to the left in order to keep your line of sight straight ahead.
So we have a Left AIC pattern which orients our pelvis, sacrum and lower spine to the right, and a compensatory Right BC pattern that counter-rotates us back to the left so that we can keep straight.
Right BC Pattern's Affect on the Ribs
The Right BC pattern is all about the position of our ribs: it positions the left and right side of our ribcage differently. What we need to focus on is the anterior aspects of the ribcage. The posterior aspect of the ribcage is important to understand when you are correcting the Right BC pattern, but to understand the pattern, just focus on the anterior ribs.
The anterior right side of our ribcage is positioned in internal rotation. Internal rotation means they are down!
The anterior left side of our ribcage is positioned in external rotation. External rotation means they are up!
To have any chance of understanding the Right BC pattern, you have to memorize what I put in bold.
Our right ribs are internally rotated and down.
The left ribs are externally rotated and up.
While leftward rotation of the torso is coming mostly from our back muscles, it is the right brachial chain muscles that all this to happen by moving the ribs. This right brachial chain activity that creates the Right BC pattern.
As a result of the Right BC pattern, the ribs get stuck in this position due to our body attempting to remain straight by rotating to the left.
The Brachial Chain Muscles
For the most part, it isn’t that important to know all the individual muscles of the brachial chain, you just have to know its influence.
The muscles are located on the front of the neck and chest and they serve to limit torso rotation to the same side. So the right brachial chain limits torso rotation to the right and the left brachial chain limits rotation to the left.
The brachial chain consists of anterior and lateral intercostals, deltoids, pectorals, Sibson’s fascia, triangularis sterni, sternocleidomastoid, scalenes, and the diaphragm.
Visual of Left AIC Right BC pattern
The picture above shows an exaggerated representation of the Left AIC Right BC pattern. My left pelvis is forward, which orients my pelvis to the right. My torso counter-rotates back to the left in order to stay straight. This counter-rotation, provided by my back muscles and assisted by the right brachial chain of muscles, results in the left anterior ribs externally rotated and elevated. You’ll often see a higher left shoulder, as well.
Breathing's Influence on Rib Position
PRI often talks about the physiologic states of inhalation and exhalation.
What this means is that when we inhale and exhale, our ribcage should be in a particular position.
When we inhale, our ribs should externally rotate and move up. This upward movement of the ribs should occur as the ribs externally rotate during ribcage expansion. This is not the same as the ribs moving straight up towards your head. A ribcage that moves straight up, rather than expand, is one that is being drawn up as a compensatory breathing pattern. Your body is attempting to “pull” your ribcage up to facilitate air flow into your chest. It uses your anterior neck muscles and upper traps to do so.
Upward rotation should occur due to ribcage expansion.
When we exhale, our ribs should internally rotate and move down.
An overactive Right BC chain of muscles, due to our torso’s need to counter-rotate back to the left on a right oriented pelvis, messes up this positional relationship.
Our ribs get stuck in one position.
On the left they get stuck in external rotation. They are elevated. They are up. They are stuck in a state of “inhalation”.
On the right they get stuck in internal rotation. They are descended. They are down. They are stuck in a state of “exhalation”.
Here is a visual of what this looks like.
In the picture above, you see ribs on the left in an elevated externally rotated position. They look more prominent than her ribs on the right.
When a torso rotates to the left, the left ribs externally rotate (move up) while the right ribs internally rotate (move down). This is what you see in the picture.
In summation, the Right BC pattern is created by the upper body’s need to stay straight on a pelvis that is oriented to the right. This leftward counter-rotation of the torso results in externally rotated ribs on the left, and internally rotated ribs on the right.
While the left counter-rotation is mostly provided by our back muscles, the right BC plays a critical role in allowing that to happen and also restricts our ability to rotate our torso back to the right.
Both brachial chains also provide an anchor that allows proper movement of the neck and cranium. But it’s the right BC that becomes the big player in limited neck and cranial movements.