ch. 21 shoulder. objectives name the three articulations that constitute the shoulder girdle...
TRANSCRIPT
Ch. 21 Shoulder
Objectives• Name the three articulations that constitute the
shoulder girdle complex. • Describe how stability of the shoulder is
maintained. • Recite the names of the four muscles that come
together to form the rotator cuff. • Explain the anatomy of the shoulder complex.• Identify major injuries and conditions of the
shoulder.
Anatomy• Ball and socket joint• most mobile joint in
the body• Humerus• Clavicle- collar bone• Scapula- shoulder
bladeo Acromion processo Coracoid process
Joints and Movements• Glenohumeral Joint-
the actual shoulder joint
• Acromioclavicular Joint• Sternoclavicular Joint• Scapulothoracic Joint
• Flexion• Extension• Abduction• Adduction• Internal Rotation• External Roation• Elevation/Depression• Protraction/Retraction
Shoulder Flexion• Pectoralis Major • Coracobrachialis• Biceps brachii• Brachialis• anterior fibers of
deltoid
Shoulder Extension• latissimus dorsi • teres major• long head of triceps• posterior fibers of the
deltoid
Shoulder Abduction• True abduction:
supraspinatus (first 15 degrees), deltoid
• Upward rotation: trapezius, serratus anterior
Shoulder Adduction• Downward rotation:
pectoralis minor, pectoralis major, latissimus dorsi
• True Adduction: same as downward rotation with addition of teres major and the lowest fibers of the deltoid
Internal Rotation• Subscapularis• Latissimus dorsi• Teres major• Pectoralis major• Anterior fibers of
deltoid
External Rotation• Infraspinatus • Teres minor• Posterior fibers of
deltoid
Elevation/Depression• Elevation
o levator scapulaeo the upper fibers of the
trapezius
• Depressiono pectoralis minoro lower fibers of the trapeziuso subclaviuso latissimus dorsi
Protraction/Retraction• Protraction
o serratus anterioro pectoralis minor and major
• Retractiono rhomboid major and minor o trapezius
Rotator Cuff • Supraspinatus• Infraspinatus• Teres Minor• Subscapularis
Muscle Force Couple• Two equal forces acting in opposite directions to
rotate a part around its axis• During shoulder abduction, the rotator cuff is
pulling down on the humeral head while the deltoid is lifting the arm.
Muscle Weakness• Most athletes have
strong anterior shoulder muscles but weak posterior shoulder muscles
• This imbalance causes forward shoulder and other shoulder injuries