Houston Methodist. Leading Medicine

Shoulder FAQ

Question:

I went with my fourth grade son on a field trip to the local museum of natural science. I noticed the skeleton on my display had a very small shoulder socket. The round part of the upper arm barely fit. Is that normal? What holds it together?

Answer:

The shoulder has the most motion of any joint in the body. To have that much mobility, the joint gives up a lot of stability. That means the head of the humerus (upper arm bone) pivots off the shoulder socket more than snapping in tightly.

In order to do this without dislocating the joint capsule, ligaments, and muscles hold it firmly in place. There's a special group of muscles that surround the shoulder called the rotator cuff. They hold the humeral head in place while allowing arm motion in all directions.

The skeleton you saw was likely very normal. But to see the bones without the soft tissues can be misleading.

Michael M. Reinold, DPT, ATC, et al. Electromyographic Analysis of the Rotator Cuff and Deltoid Musculature During Common Shoulder External Rotation Exercises. In Journal of Orthopaedic & Sports Physical Therapy. July 2004. Vol. 34. No. 7. Pp. 385-393.

*Disclaimer:* The information contained herein is compiled from a variety of sources. It may not be complete or timely. It does not cover all diseases, physical conditions, ailments or treatments. The information should NOT be used in place of visit with your healthcare provider, nor should you disregard the advice of your health care provider because of any information you read in this topic.
All content provided by eORTHOPOD® is a registered trademark of Medical Multimedia Group, L.L.C.. Content is the sole property of Medical Multimedia Group, LLC and used herein by permission.

Our Specialties

Where Does It Hurt?

Our Locations

  Follow Us

Follow us on Facebook Follow us on YouTube
Follow us on Twitter