A Review of the Shoulder Muscles and Their Actions

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A Review of the Shoulder Muscles and Their Actions
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Questions

• What muscle works closely with the anterior
  deltoid?
• Pectoralis major
• What muscle is involved in any lifting movements?
  
• Deltoid
• What is the major (strongest) extensor muscle?
• Latissimus Dorsi
• Name the four rotator cuff muscles.
• Subscapularis, Supraspinatus, Infraspinatus, and
  Teres minor.
• What muscle works closely with the infraspinatus?
• Teres minor

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Practice

• Name the muscles for Horizontal Adduction
• Pect Major (both)
• Corachobrachialis
• Deltoid (anterior)

• Name the muscles for Horizontal Abduction
• Deltoid (post)
• Infraspinatus
• Teres minor
• Lats

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Practice

• List the muscles that do flexion of the shoulder
• Coracobrachialis
• Pectoralis major (upper to 60)
• Anterior Deltoid

• List the muscles that do extension of the
  shoulder
• Latissimus dorsi
• Teres major
• Posterior deltoid
• Pectoralis major (lower fibers to neutral)

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Practice

• List the muscles that do adduction of the
  shoulder
• Pectoralis major (lower and upper below 90)
• Coracobrachialis
• Latissimus dorsi
• Teres major

• List the muscles that do abduction of the
  shoulder
• Deltoid (all sections)
• Supraspinatus
• Pectoralis major (upper past 90)

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Practice

• List the muscles that do internal rotation of the
  shoulder
• Subscapularis
• Latissimus dorsi
• Teres major
• Anterior deltoid
• Pect. major

• List the muscles that do external rotation of the
  shoulder
• Infraspinatus
• Teres minor
• Posterior deltoid

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Name the muscle.
Coracobrachialis
Name the action
Adduction of the shoulder Also, flexion and hor.
add.
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Name the muscle.
Pectoralis Major
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Name the muscle.
Subscapularis
Name the action
Internal rotation of the shoulder
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Name the muscle.
Deltoid
Name the action
Abduction of shoulder
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Name the muscle.
Infraspinatus
Name the action
External rotation
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Name the action
Name the muscle.
Adduction of scapula
Teres Major
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Name the muscle.
Teres Minor
Name the action if the humerus move directly to
the posterior
Extension of the shoulder
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Name the muscle.
Supraspinatus
Name the action
Abduction of the shoulder
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Coracobrachialis
Pect. Major
Subscapularis
Deltoid
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Supraspinatus
Teres Major
Infraspinatus
Teres Minor
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What position are her shoulders in?
Flexion
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What position is his right shoulder in?
Horizontal Abduction and External Rotation
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What rotation action is his shoulder performing
as he continues to through the ball?
Internal Rotation
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What position are her shoulders in?
Flexion
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What position are his shoulders in?
Horizontal abduction or Extension
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Position of their shoulders?
2.
1.
Extension
Flexion
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What is the position of shoulders?
Extension
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Shoulder Muscle Exercises
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Major Muscles of the Shoulder

• Pectoralis major
• Push-ups
• Pull-ups
• Bench press
• Throwing
• Tennis serve

• Latissimus dorsi
• Chinning
• Robe climb
• Dips on parallel bars
• Pullover exercises
• Pulldown exercises
• Rowing

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Shoulder action ? Shoulder muscle(s) ?
Deltoid Supraspinatus
Abduction
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Shoulder action ? Shoulder muscle(s) ?
Flexion
Ant Deltoid Upper Pect Major Coracobrach.
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Shoulder action ? Shoulder muscle(s) ?
Ant. Deltoid Pect. Major (both) Coracobrachialis
Horizontal Add.
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Shoulder action ? Shoulder muscle(s) ?
Horizontal Abduction
Latissimus Dorsi Post. Deltoid Teres
Minor Infraspinatus
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Shoulder action ? Shoulder muscle(s) ?
Adduction
Pect. Major (both) Coracobrachialis Latissimus
Dorsi Teres Major
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Shoulder action ? Shoulder muscle(s) ?
Horizontal Add
Ant. Deltoid Pect. Major (both) Coracobrachialis
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Shoulder action ? Shoulder muscle(s) ?
Extension
Lats Teres Major Post. Deltoid Pectoralis Major
(lower) Infraspinatus Teres minor
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Shoulder action ? Shoulder muscle(s) ?
External Rotation
Infrspinatus Teres Minor Post. Deltoid
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Name a shoulder muscle isolated with the
following exercises.

• Side arm dumbbell raises
• Deltoid
• Push-ups
• Pectoralis major
• Rowing and pull-overs
• Latissimus dorsi

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What is the action to the left? What muscles
perform that action?
External Rotation
Internal Rotation
Internal Rotation
Subscapularis, Ant. Deltoid, Pect, Major, Lats.
And Teres Major
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Rotator Cuff Exercises
External Rotation
Internal Rotation
External Rotation
Abduction (to work the supraspinatus)
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Shoulder Related Injuries

• The shoulder is built for motion, not stability
• Injury rate depends on
• Shallowness of glenoid fossa
• Laxity of ligaments
• Strength of muscles

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• Shoulder subluxation
• Incomplete or partial dislocation
• Shoulder dislocation
• Complete dislocation of the GH joint
• Most common anteriorly and inferiorly
• Shoulder separation
• Complete dislocation of the AC joint

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Shoulder Dislocation
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Impingement Syndrome
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Impingement Syndrome

• A condition that decreases the subacromial space
• Acromion process
• Coracoacromial ligament
• Causes
• Swelling
• Bone spurs
• Anatomical structure 

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Impingement Syndrome
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Rotator Cuff Tears
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Rotator cuff

• Subscapularis
• Supraspinatus
• Infraspinatus
• Teres minor

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Movement of RC Muscles

• Subscapularis is an internal rotator of the arm.
• Supraspinatus assists the deltoid in abducting
  the arm, with its greatest contribution being the
  initiation of abduction.
• Infraspinatus and teres minor muscles both
  externally rotate the arm.

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Rotator Cuff Injury

• The throwing motion has been divided into five
  phases wind-up, cocking, acceleration, and
  follow-through.
• Cocking phase
• Subscapularis fires in late cocking phase to
  decelerate the shoulder's external rotation.
  Also, it is stretched during the cocking phase.

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Rotator Cuff Injury

• Follow-through (muscles fire most intensely)
• Subscapularis internally rotates the shoulder,
• The infraspinatus and teres minor contract
  eccentrically to decelerate the arm and are
  stretched.
• During this repetitive eccentric loading, the
  rotator cuff is prone to overload, fatigue,
  tendinitis, and even a partial undersurface tear.

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Note Surgery needs to be performed within 3
months or the supraspinatus muscle will atrophy
and be too short to reattach
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Glenoid Labrum
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Labral Tear

• The glenoid cavity makes up the socket of the
  shoulder joint. 
• The labrum acts sort of like a gasket, turning
  the flat surface of the glenoid into a deeper
  socket that molds to the head of the humerus for
  a better fit.
• A tear of labrum can cause pain and a catching
  sensation with movement of the shoulder. 

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Labral Tear

• Most labral tears are probably the result of an
  injury to the shoulder, such as falling on an
  outstretched hand. 
• There is reason to believe that the excess motion
  of the humerus moving around on the glenoid may
  cause damage to the labrum over time.  
• An unstable shoulder may also cause injury to the
  labrum, if it repeatedly dislocates out of the
  glenoid.