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Origin Size vs. Muscle Size

Don’t judge the size or power of a muscle by the shape of its attachment.

It’s a simple point that’s worth remembering.

As Jon Zahourek makes clear in the brief clip below, there’s more to supraspinatus and infraspinatus than the triangles you might draw to show where the muscles attach. One thing about building the muscle in clay, and watching it fill out the model scapula, is you get a better feeling of the relative of the muscle.

The bony septum, or wall, that separates the two muscles creates much more surface area for both supraspinatus and infraspinatus to function.

Supraspinatus will never show up on a list of the largest muscles in the human body but in its realm, the rotator cuff, it’s more powerful than it might at first let on.

And consider all the ways supraspinatus interacts with the other muscles in the rotator cuff, which makes all those shoulder movements possible.

What are the four muscles of the rotator cuff?

An easy acronym, SITS, will help you remember:



Teres Major


Have you tried building the rotator cuff on the 60% life-sized MidiMANIKEN™ Shoulder Model?

View complete collection of "Anatomy Insights with Jon Zahourek" videos.






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