Dissection of upper limb movement

Shoulder is a complex joint. For  shoulder flexion to get the arm overhead – 12 ribs and their vertebral attachments and 10 with sternal attachments, scapular motion through 3 dimensions (frontal plane, saggital plane, and transverse plane rotations), humeral rotation and alignment within the glenoid fossa, AC and SC joint motions or limitations, vertebral motion of at least the 12 thoracic vertebral segments, and  finally local muscular issues – means to get your arms in the air to wave them like you just don’t care can take motion from 38 joints through 3 planes of action and muscular actions from at least 24 muscles that attach through the thoracic spine, scapula and humerus.

It’s tough for the scapulae to retract and depress if the person has rounded shoulder (i.e.rib cage is stuck in flexion.)

In terms of scapular motion, the shoulder blades have the ability to move through 3 planes due to their floating attachment to the body.

For rotation, the scapula rely on triangulation force application from 3 different muscle groups to create upward rotation and 3 different groups to produce downward rotation.

During upward rotation movements,

[restrict] sufficient scapulohumeral rhythm should be 1:2, where the humerus moves 2 degrees for every degree that the scapula rotates. For reference, when the arm is overhead at 180 degrees of flexion, the scapula should be rotated to 60 degrees (180-60 = 120, maintaining the 2:1 ratio).

When that scapular rotation doesn’t happen and they wind up shrugging the shoulder to get it into place, essentially substituting torso side bending for scapular motion. There could also be adhesive changes in the shoulder joint itself, a condition commonly known as frozen shoulder, and in this instance the rhythm goes from 2:1 down to 1:1, where pretty much all of the movement comes from the shoulder blade and none comes from the humerus itself.

A side from upward and downward rotation, there is  also forward tilting and backward tilting of scapula . Forward tilt is also commonly called winging scapula.(when there is under active of serratus anterior)

By itself, a winged scapula isn’t a problem, but it is a graphic example of a shoulder that may not have positional strength or stability to get the blade flat to the spine(Poor motor control of scapula). In order to find stability, the shoulder blade winds up peeling off the torso and angling forward, making it difficult to adequately retract or rotate.

Typically working to improve winging involves directly training the serratus anterior to help promote protraction, however in my experience the serratus isn’t weak but constantly on, and you can barely palpate the lower traps and rhomboids because they’re fairly atrophied. In many ways, a winging scapula isn’t a single muscle problem, but a systemic  compensation. Pretty much all of the muscles attaching to the scapula need to be strengthened .

Again, This just illustrates the rotational capability of the shoulder blade outside of upward or downward rotation. This type of tilting works through the transverse plane in relation to the torso, but there’s also saggital tilting.

This is common with people who have significant thoracic rounding into kyphosis, as well as a forward head posture. It’s challenging to do anything with the shoulder blades other than elevate and protract in this position without addressing thoracic motion first, hence breathing mechanics to try to pull them away from the flexion bias towards more extension positional aptitude.

A lot of these motions can be helped or hindered through common muscle training and posture work, but some is affected through degenerative or injurious tendencies through the AC joint and SC joint.

Many people with degenerative issues such as arthritis tend to also develop some significant reductions in movement capability through the SC joint, which should be able to rotate, elevate and protract relatively easily. If it’s stuck, the shoulder blade won’t move.

So in terms of getting the shoulder blade to move, there’s a bunch of different ways. Principally, just make it move through the basic patterns of protraction, retraction, elevation, depression, upward and downward rotation and you’ll have your bases covered. Just make sure the movement is in the direction you want .

You could do any of these exercises, or different ones if you want. As long as the movements work that’s all that matters. If you can’t get a specific movement to work, spend some more time on correct inhibited structure.Especially if that movement is important to any activity you want to do. For example, if you can not get your movement  easily , you should  locked up for thoracic spine or poor positioning to accommodate the movement, spend some time trying to adjust your thoracic positioning and mobility to allow an easier time to access those movements.

Drilling ROW Movement:

Prior to starting any of the scapular movements, look at the thoracic spine, as we discussed earlier. A rounded thoracic spine will make retraction and rotation difficult. A hyper extended spine will make elevation and protraction difficult.

The lattismus  muscle causes the humerus to extend and externally rotate, and pulls the scapula into retraction and depression. If you’re doing a row and your shoulder blade winds up in your ear with the hand on your chest and elbow out in the boonies away from your body, you’re not using your lat. Do you want to use your lat? Yes, you do, especially when doing a row, so therefore you need to adjust how those shoulders move .

Next, look at glenohumeral motion. The basic stuff to check are external rotation and internal rotation, as well as both rotations through specific positions like with the arm abducted, addicted, or where ever you’re going to need to have rotational control. If you want to do muscle testing on the muscles controlling these motions, have at it.

I can see in my practice that many people complains about shoulder or back pain after joining gym. What I observe is there is lack of understanding of joint position performing exercise. There is also lack of flexibility issue.

To press a bar overhead requires a fair amount of GH internal rotation (biceps wind up pointing towards ears = IR). To bench press requires similar internal rotation. To squat, do lat pull downs behind the head, or thumbs up rear delt raises all take more external rotation, so understanding what movements you have control over and available can make difference in your exercise selection and relative risk of injury with each exercise.

                   Take home message

There are  bunch of contributing factors that can affect shoulder motion. From the above discussion always start with  thoracic positioning, scapular motion, and finally look at glenohumeral motion when dealing with tricky shoulder movements that just aren’t giving you what you want.


 1)  Functional anatomy of the shoulder : . 2000 Jul-Sep; 35(3): 248–255.


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