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Anatomy Primer and Device Concept

Home|About The ShoulderSphere -1|Anatomy Primer and Device Concept

Three bones converge to form the shoulder joint. These are the collar bone – the clavicle. The shoulder blade – the scapula. And the arm bone itself – the humerus.

The shoulder is NOT a “ball-in-socket” joint like a baseball in the catcher’s mitt, but rather resembles that of a golf ball sitting on a tee where only a third of the surface area of the humeral head is in contact with the glenoid bony portion of the scapula.

Stability of this very mobile shoulder joint is dynamically produced by compression of the humeral head against the glenoid during movements of the shoulder. This compressive force is generated by the coordinated contraction of the deep layer muscles that surround the humeral head – the ROTATOR CUFF : three from the back and one from the front. Additionally, the ROTATOR CUFF muscles ROTATE the shoulder.

Superficial to the deep ROTATOR CUFF MUSCLES are the larger and more powerful muscles, namely – the deltoid, the trapezius, and the pectoralis. All together, no less than seventeen muscles are involved in shoulder motion, but only four, the ROTATOR CUFF MUSCLES, stabilize and keep the humeral head depressed abutting securely against the glenoid to maintain the smooth rotational movement of the shoulder during motion.

When the ROTATOR CUFF MUSCLES are weak, or with tears of the ROTATOR CUFF TENDONS, they no longer are able to balance the upward pull of the deltoid. This creates an upward abnormal motion of the humeral head as one tries to raise the arm. Likewise, the humeral head may move abnormally forward during throwing activity when the ROTATOR CUFF is not able to maintain the posterior balance needed to offset the forward translational force in throwing. In bench press weight lifting activity, the humeral head will tend to be pushed backwards when the weight in front of the shoulder overwhelms the check rein strength needed to keep the humeral head centered against the glenoid. These abnormal translational or microsubluxation movements of the humeral head will push and tear the surrounding ligaments resulting in so-called labral tears. This leads to pain, muscle shut down, more weakness, and set up the vicious spiral downhill cycle with more pain and more instability leading ultimately to painful arthritis of the shoulder joint.

Maintenance of ROTATOR CUFF strength is an indispensable part of shoulder health and function.


Unfortunately, it is difficult to isolate the deeper ROTATOR CUFF MUSCLES from the superficial muscles using the current so-called ROTATOR CUFF strengthening exercises. These exercises, although try to focus on the function of the ROTATOR CUFF such as external or internal rotation of the shoulder, lack specificity, efficiency, and effectiveness. The reason being these exercises are linearly driven, one direction, and one muscle at a time.

An innovative game changer that will lead the future of ROTATOR CUFF strengthening is the ShoulderSphere. Understand that the function of the ROTATOR CUFF is to ROTATE the shoulder, the ShoulderSphere exercise principle is rotational training of ALL the ROTATOR CUFF MUSCLES in a SIMULTANEOUS and MULTIDIRECTIONAL manner.

Finally, a safe, efficient, and effective ROTATOR CUFF strengthening exercise technique has arrived!

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