Rodney McBride



Hopefully by now if you have read my last three blogs Another Look at the Spine (see October 6th), Another Look at the Spine 2 (see October 20th) and Coupled Motion (see November 3rd) you have a nice understanding of how rotational actions of the vertebrae can allow larger movements to happen. 

Remember that I am not talking about gross rotational patterns as in rotating the entire spine to one side. I am talking about the finite rotational capability of each individual vertebra separate from its neighbor. This is only a few degrees of rotation left or right but has a tremendous influence on spinal mechanics.

Today I will finish off on this topic by talking about the final piece of spinal function and that piece is called PiLUS (Even though there is an i in the acronym PiLUS it is still pronounced PLUS as if there were no i at all).  

Each letter in PiLUS represents a muscle. The P stands for Piriformis, the i for iliacus, the L for Latissimus dorsi, the U for Upper trapezius and S for Sternocleidomastoid. All five muscles assist the spine in forward flexion (bending forward). 

More specifically the right Piriformis, the right iliacus, the left Latissimus dorsi, the left Upper trapezius and the right Sternocleidomastoid assist the spine in forward flexion. 

When you flex forward at the waist the spine cannot do it in one segment. Certain vertebrae have to rotate out of the way first. The vertebrae would jam into one another in flexion if they didn't rotate.

In forward flexion the sacrum will rotate back and the fifth lumbar (L5) will counter rotate forward. Every vertebra from that point on will rotate left or right depending on which muscle is connected. 

The five muscles involved actually inhibit (turn off) in forward flexion. This inhibition pattern allows the vertebrae to rotate in sections so forward flexion can commence. This function is normal and is also relevant with extension and gate. 

You have to bend forward or back approximately 30 degrees in order for PiLUS to activate. If any or all five of these muscles don't inhibit then you have another issue that needs to be addressed.

Not getting an inhibition response when checking PiLUS can put unwanted compressive forces on the vertebral discs and nerves. If you already have back problems it's something else that can exasperate an already compromised situation. Get it checked.

PiLUS is like the icing on the cake. Once I have corrected everything else I check PiLUS and other systemic functions to see if they are operating in the right manner.

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