The Infraspinatus Muscle

In my last post, Trigger Points (TrP’s) In Detail, I briefly mentioned a TrP in the infraspinatus and thought I would go ahead and write about this muscle more thoroughly since it is a big player with shoulder issues.

THE ANATOMY (per Tortora & Derrickson, 11th edition)
Origin: Infraspinous fossa of scapula.
Insertion: Greater tubercle of humerus.
Action: Laterally rotates and adducts arm at shoulder joint.
Innervation: Suprascapular nerve.

The infraspinatus is one of the four deep muscles that join the scapula to the humerus. The four tendons merge together to form the rotator cuff. The rotator cuff strengthens and stabilizes the shoulder joint and is comprised of the supraspinatus, infraspinatus, teres minor, and subscapularis; think S-I-t-S (small “t” representing the teres minor–not major).

The prime function of the infraspinatus is to decelerate forward motion of the humerus. Repetitive movements with the arm in over-the-head positions—such as in throwing a baseball, a tennis serve, spiking a volleyball, and swimming—can result in injuries. This happens because much of the work of the infraspinatus is done in eccentric contraction. Eccentric contraction is when the muscle fibers lengthen during contraction… More on muscle contractions in my next post.

Great info, Nicole, but how does one know if the infraspinatus needs some TLC from a CPNMT (Certified Precision Neuromuscular Therapist)?

LOL! That last sentence is so ridiculous. 🙂

Well, some general indicators for treatment could include, but are not limited to:
1) Difficulty brushing or combing your hair;
2) Inability to sleep on your side at night;
3) Inability to reach behind your back and touch the opposite shoulder blade.

There are other—more medical—indicators for treatment, which is why I recommend contacting myself or another CPNMT for an evaluation if you are experiencing problems within the shoulder girdle.

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“Neutral balance alignment is key to becoming pain free!”™ ~ Me