Scapula Movements & Muscle Involvement
1) Retraction (adduction): rhomboids, upper-mid-lower trapezius
2) Protractoin (abduction): serratus anterior
3) Elevation: upper traps, rhomboids, and levator scapula
4) Depression: lower trapezius, pectoralis minor, lower serratus anterior
5) Upward rotation: upper-lower trapezius, serratus anterior
6) Downward rotation: rhomboids, levator scapulae
Shoulder Joint
1) Acromio-Clavicular joint (A/C joint) - shoulder blade (scapula) meets collarbone (clavicle)
2) Gleno-Humeral joint (G/H joint) - shoulder blade meets upper arm bone (glenoid fossa/humerus) ball and socket joint
Major Shoulder Muscles
1) Deltoids: anterior head - pulls the arm up to front/ shoulder flexion
lateral (medial) head - pulls the arm up to the side/shoulder abduction
posterior head - pulls the arm horizontally from across the body/ shoulder abduction
2) Pectoralis major & minor - pulls arm across the chest (upper, middle, lower) and assist in internal rotation / horizontal shoulder adduction and assist in internal rotation.
3) Latissimus dorsi and teres major - pulls arm down, pulls arm back, and assist in internal rotation
4) Biceps brachii and brachioradialis - assist in raising arm to the front & flexes arm
5) Triceps medial/lateral/long - pulls the arm down at the shoulder either from the front or from the side and extends the arm.
Rotator Cuff Muscles "SITS"
1) S upraspinatus (top) - keeps the humerus from falling downward out of the shoulder socket.
2) I nfraspinatus (rear) - runs from the back of shoulder blade to the back of the humerus.
3) T eres minor (rear) - same as infraspinatus
4) S ubscapularis (rear) - runs from the underside of the shoulder blade to the front of the humerus.
* Internal rotator cuff muscles: pecs, lats, teres major, subscapularis
* External rotator cuff muscles: infrapinatus, teres minor
Function of "SITS" Muscles
1) When medial deltoid contracts the subscapularis, infraspinatus, teres minor pull down on the humerus just enough to prevent the humerus from hitting the roof of the acromion (socket).
2) The "SITS" muscles work as stabilizers for all major upper body motions.
3) If the rotator cuff is compromised, through weakness or injury, the prime and secondary movers cannot act effectively at the joint, regardless of how strong the prime and secondary movers are.
4) The "SITS" muscles are involved in decelerating the arm during throwing motions.
5) The primary external rotators of the arm are infraspinatus and teres minor and the supraspinatus assists the internal rotation of the arm.
Concerns for Rotator Cuff Muscles
1) If you raise your arm in an internally rotated position (with your palm facing back and your thumb pointing down), its inevitable: the greater tubercle (top of humerus) will run into the acromion (top of socket).
2) Everyone over 60 will have some degeneration in the rotator cuff muscles and athletes can certainly accelerate the degenerative process well beyond what is expected for an athlete's chronological age.
3) Inflammation of one of the rotator cuff tendons is called tendonitis. The most commonly affected is the "supraspinatus" tendon. Keep in mind that inflamed tendons need absolute rest, 3-4 times daily ice, mild anti-inflammatory, and medical opinion on the exact diagnosis. If you irritate the tendon then you have inflamed the tissue once again and you would be foolish to try and work through injuries of this nature.
4) Tendonitis is unusually the result from a combination of two things:
a. Performing exercise improperly (repetitive stress disorder)
b. Overtraining (not enough recovery)
c. Doing split routines that work the rotator cuff muscles with only 24 hours recovery (example would be all pushes on Monday followed by all pulls on Tuesday)
5) Most common "rotator cuff tears" affect the supraspinatus and its tendon. Younger athletes usually avulse the tendon (tear tendon off the bone at insertion site) rather than sprain it. A tear in the muscle is called a "strain" and a tear in the ligament is called a "sprain."
6) "Impingement" occurs between the greater tubercle and the acromion. Most commonly affects the supraspinatus tendon, the tendon of the long head of the biceps, and the shoulder bursa. Some people are born with very little space between the head of the humerus and the acromion. This puts them at greater risk of impingement.
Exercises that could cause impingement:
1. Lat pull downs behind the neck (most men have limited external rotation of the shoulder)
2. Pull-ups behind the neck (same as above)
3. Seated presses behind the neck (same as above)
4. Upright row and DB pullover (impingement of A/C or G/H joint)
5. Wide grip bench press and bar too high on chest Impingement A/C
6. Elbows flaring back (not straight down to floor) when performing pulldowns and seated presses.
7. Raising arms above the shoulder during lateral raises
8. Doing shoulder internal and external rotation movements incorrectly.
7) "Adaptive shortening" involves a loss of muscle flexibility that is resistant to being stretched: "muscle imbalance" that is created by over emphasizing the internal rotators (lats, pecs, teres major, subscapularis) and undertraining the external rotator (infraspinatus, teres minor) muscles. Result is "adaptive shortening" of internal rotators.
8) "Fibrosis" (scar tissue) are adhesions that form due to the following training mistakes:
a. Repeated biomechanically unsound exercises (repetitive stress disorder)
b. Lifting with restricted range of motion
c. Training the same area of the body too often
d. Training with too much weight
e. Excessive bench press and push movements (imbalance)
The Cure and Prevention
1) Strengthen the external rotator cuff muscles
2) Stretch the internal rotator cuff muscles
3) Eliminate training errors that promoted dysfunctional shoulder biomechanics in the first place
4) Modify exercises to eliminate any discomfort to the shoulder girdle
a. Decrease weight slow down reps (4/4 count)
b. Emphasis either more or less time on concentric or eccentric
c. Decrease weight, increase reps, and control the weight
d. Change seat height or position to avoid specific angle of discomfort
e. Dumbbells can help you avoid specific angles of discomfort
f. Perform exercise one arm at at time.
g. Modify the starting position of tension/ pin-up or weight stack
h. Change exercise modality: free weight/DB/machines/cables
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