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Shoulder

Image result for anatomy of the shoulder bones

The shoulder is in fact a complex that consists in three bones;  the humerus, the upper arm bone, the scapula, the shoulder blade, and the clavicle, the collarbone. Those bones form four joints;
    the glenohumeral joint (Shoulder Joint):  you’ll often hear it referred to as simply the shoulder joint. The glenohumeral joint connects the upper arm bone to the shoulder blade.  It is a ball and socket joint. The head of the upper arm is shaped like a ball which sits in a shallow socket at the lateral end of the shoulder blade;
    the acromioclavicular joint: the acromioclavicular joint connects the collarbone with the shoulder blade;
    the sternoclavicular joint: the sternoclavicular joint connects the collarbone with the breastbone;
    the scapulothoracic joint: is not really a joint. The shoulder blade sits on the back of the rib cage and moves up and down and rotates with shoulder movement.

Image result for shoulder blade posture

All three joints work together to allow movement of the arm in all directions. We are treating the shoulder movments as if there was only one joint but note that it is more complex than that.
By itself, the shoulder blade is not very mobile but unbalance in the muscles stabilizing it will contribute to the overall lack of performance of the shoulder.  The movements of the shoulder other than the glenohumeral joint, are depicted in the figure.

Movements

Flexion - Extension

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Flexion: Bending the joint resulting in a decrease of angle; moving the upper arm upward to the front. Typically accompanies Shoulder Girdle Elevation Upward Rotation
Range of motion: 90-100°.

Extension: Straightening the joint resulting in an increase of angle; moving the upper arm down to the rear. Typically accompanies Shoulder Girdle Depression Downward Rotation.
Range of motion: 40-60°.

Abduction - Adduction

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Abduction: Lateral movement away from the midline of the body; moving the upper arm up to the side away from the body. Typically accompanies Shoulder Girdle Upward Rotation
Range of motion: 90-95°

Adduction: Medial movement toward the midline of the body; moving the upper arm down to the side toward the body. Typically accompanies Shoulder Girdle Downward Rotation
Range of motion: 75°.

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Internal - External Rotation

Internal rotation: Rotary movement around the longitudinal axis of the bone toward the center of the body; turning the upper arm inward. Typically accompanies Shoulder Girdle Protraction.
Range of motion: 70°.

External rotation:  Rotary movement around the longitudinal axis of the bone away from the center of the body; turning the upper arm outward. Typically accompanies Shoulder Girdle Retration.
Range of motion: 90°.

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Horizontal Abduction - Adduction

Horizontal abduction:  Lateral movement away from the midline of the body in a horizontal plane; moving the upper arm away from the chest with the elbows facing down. Typically accompanies Shoulder Retraction.
Range of motion: 45°.

Horizontal adduction:  Medial movement toward the midline of the body in a horizontal plane; moving the upper arm toward and across the chest with the back of the arm facing down. Typically accompanies Shoulder Protraction.
Range of motion: 135°.

Muscles

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Flexion: Deltoid, Pectoralis major (clavicular head), Coracobrachialis, Biceps brachii (short head).
Extension: Latissimus dorsi, Deltoid (posterior), Pectoralis major (sternal head), Teres major, Triceps brachii (long head).
Abduction: Deltoid (lateral), Deltoid (anterior), Suprospinatus, Pectoralis major (clavicular head).
Adduction: Latissimus dorsi, Pectoralis mojor (sternal head), Pectoralis major (clavicular head), Teres major, Coracobrachialis, Triceps brachii (long head).
Horizontal abduction: Deltoid (posterior), Deltoid (lateral), Infraspinatus, Teres minor.
Horizontal adduction: Pectoralis major (sternal head), Pectoralis major (clavicular head), Coracobrachialis.

Evaluating movement dysfunction

Mobility Evaluation Shoulder
Strength Evaluation: Shoulder
Posture evaluation: might reveal a bad position of the shoulder and shoulder girdle at rest.
FMS: Shoulder Mobility, this test gives an overall view of the shoulder mobility.  The evaluation of the mobility of specific movements is needed to pinpoint the problem.
       Deep squat, can provide indication of shoulder lack of mobility if the athlete is not able to put the stick directly above his head.


Image result for shoulder blade posture

Scapula Retraction

Constitutes a poor alignment of the shoulder at the scapula level.  It can influence performance in running and throwing by affecting the mobility and strength of the shoulder.
Corrective measures:
   Strength: Shoulder Girdle Strength
    Mobility:YW Stretch