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02-16-2013, 11:26 AM
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Not wanting to prolong the fascinating exchange of medical information, here is a clarification of terms.

There are two "joints" at the "shoulder":

1) The glenohumeral joint is a "ball and socket" joint where the humerus (upper arm bone) connects to scapula ("shoulder blade") at the glenoid cavity ("socket"). A number of injuries can affect that region, with perhaps the most common sports injury being a subluxation (or "dislocation"). That happens when the humerus ("ball") dislocates out of the socket. This often comes with some tearing of connective tissue, and can become a chronic problem.

2) The acroclavicular joint is where the clavicle ("collar" bone) connects to the acromion of the scapula. This is a "fixed" joint for overall stability, with the end of the clavicle ("collar" bone) tethered tightly to the acromion (at the "shoulder") by strong ligaments. A common injury at this joint occurs in contact sports when the trauma causes the ligaments to tear and the joint "separates". This is often called a "separated shoulder", and comes in degrees (from a complete separation, where ligaments are completed torn to lower grades where they are partially torn). Another injury is a fracture of the clavicle ("collar" bone) where trauma causes the strong bone to fracture ("broken collar bone").

Beyond these types of injuries, the upper arm bone (humerus) can also sometimes fracture.

Here's a picture to help folks think this through...

But perhaps we should just leave it at "upper body injury", for simplicity.

Last edited by Whileee: 02-16-2013 at 11:32 AM.
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