Southwest Orthopaedic Physical Therapy Information Headquarters

The Amazing Shoulder

Posted by Dani Livsie on Mar 1, 2011 1:02:00 PM

ShoulderThe human shoulder can do incredible things.It allows us to perform any and every overhead activity. It is the foundation of the upper limb that allows our hands to perform highly skilled activities such as paint, play a musical instrument, or accurately throw a ball.In this article, I would like to point out some characteristics that make the shoulder joint truly unique.

     The shoulder joint is the most proximal or closest joint that connects the entire upper limb to the trunk. It is called a "ball and socket" joint. In comparison, the hip joint is also the most proximal or closest joint but connects the trunk to the lower limb and it too is a "ball and socket joint".

Let's contrast & compare the two:                                       

*The cup or "socket" of the hip joint is embedded into the bottom of the pelvis making it very sturdy and stable in order to accept the weight of thehead, trunk, and arms.                         

*The cup or "socket" of the shoulder is a part of the shoulder blade or wing-bone.

*The complicated part about this is the shoulder blade is NOT directly attached to the trunk, through a bony joint.Therefore,the cup of the shoulder joint is not embedded into the trunk like the hip socket is.                                                        

*Instead, the shoulder blade is held onto the trunk by 11 different muscles! The only bony joint that attaches the entire upper limb to the trunk is the tiny little joint connecting the collarbone to the sternum or breastbone!                                                          

This does 2 things to the human shoulder:         

1. It allows our upper limb to be incredibly mobile, flexible, and coordinated.                                                                           2. Unfortunately,it makes our shoulder significantly less stable making it susceptible to dislocation and other injuries. 

So there you have it. The amazing shoulder making us truly amazing individuals. Thanks for reading. We appreciate each and every one of you..............Kale

Topics: health, physical therapy