Download Stability If you`re going to describe the joints that make up the

Stability
If you’re going to describe the joints that make up the shoulder
girdle- what order would you do that in?
1.
2.
3.
4.
Sternoclavicular (SC) joint (no muscles; all ligaments)
Acromioclavicular (AC) joint (no muscles; all ligaments)
Glenohumeral (GH) joint (has both muscles and ligaments)
Scapulothoracic articulation (all muscle)
Mobility
If you’re going to describe the motions you may explain some of that
within the section above, until you get to the GH- which is different
than the others.
Biomechanics
Why is the GH joint different than the others? How does it
move? How does the movement of the AC and SC facilitate the
movement of the GH? In what order should you discuss movement of
the GH joint? The scapular stabilizing muscles play a major role here
to stabilize the scapula- but stabilize for what reason?
Order and organization are the first things that I’d comment on here. If we
talk about shoulder function it probably makes sense to start proximal and
work distal to describe attachment points: SC > AC > GH
These joints
enable 3 deg of freedom. From there you can discuss groups of muscles by
functions- muscles in the front do anterior type movements (Flexion and
horizontal adduction) – muscles in the back do the opposite. Group the
rotator cuff to discuss rotation and joint compression. Then biomechanics at
the end- which means working distally to proximally. Humerus moves and
b/c of the coracoacromial arch the scapula gets pushed into rotating as much
as 60 deg. Six muscles stabilize and support that scapular rotation- identify
them. As the scap moves it puts stress on the AC joint allowing 30 deg of
elevation within the first 90 deg of GH abduction. As it reaches its limit the
clavicle elevates putting stress on the SC joint creating 30 deg of elevation
there. 30 and 30 equals the 60 deg of elevation the scap needs to rotate to
support 180 deg of abduction.