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• Shoulder girdle (scapulothoracic)Shoulder girdle (scapulothoracic)– scapula moves on the rib cagescapula moves on the rib cage– joint motion occurs at sternoclavicular joint joint motion occurs at sternoclavicular joint
& to a lesser amount at the & to a lesser amount at the acromioclavicular jointacromioclavicular joint
• anteriorly 15 degrees with protractionanteriorly 15 degrees with protraction• posteriorly 15 degrees with retractionposteriorly 15 degrees with retraction• superiorly 45 degrees with elevation superiorly 45 degrees with elevation • inferiorly 5 degrees with depressioninferiorly 5 degrees with depression
• Sternoclavicular (SC)Sternoclavicular (SC)– Ligamentous supportLigamentous support
• anteriorly by the anterior SC ligamentanteriorly by the anterior SC ligament• posteriorly by the posterior SC ligamentposteriorly by the posterior SC ligament• costoclavicular & interclavicular costoclavicular & interclavicular
ligaments provide stability against ligaments provide stability against superior displacementsuperior displacement
• ScapulothoracicScapulothoracic– not a true synovial jointnot a true synovial joint– does not have regular synovial featuresdoes not have regular synovial features– movement depends on SC & AC joints movement depends on SC & AC joints
which allows the scapula to move which allows the scapula to move • 25-degrees abduction-adduction25-degrees abduction-adduction• 60-degrees upward-downward rotation60-degrees upward-downward rotation• 55-degrees elevation-depression55-degrees elevation-depression
– supported dynamically by its musclessupported dynamically by its muscles– no ligamentous supportno ligamentous support
• Focus on specific Focus on specific bony landmarksbony landmarks– inferior angle inferior angle – glenoid fossa glenoid fossa – acromion processacromion process
• Shoulder joint & shoulder girdle work Shoulder joint & shoulder girdle work together in carrying out upper extremity together in carrying out upper extremity activitiesactivities
• Shoulder girdle movement is not Shoulder girdle movement is not dependent upon the shoulder joint & its dependent upon the shoulder joint & its musclesmuscles
• Shoulder girdle musclesShoulder girdle muscles– Stabilize scapula so the shoulder joint Stabilize scapula so the shoulder joint
muscles will have a stable base from which muscles will have a stable base from which to exert force for moving the humerusto exert force for moving the humerus
– Contract to maintain scapula in a relatively Contract to maintain scapula in a relatively static position during shoulder joint actionsstatic position during shoulder joint actions
– Contract to move shoulder girdle & to Contract to move shoulder girdle & to enhance movement of upper extremity enhance movement of upper extremity when shoulder goes through extreme when shoulder goes through extreme ranges of motionranges of motion
• For some shoulder girdle movements, For some shoulder girdle movements, scapula must rotate or tilt on its axisscapula must rotate or tilt on its axis
• Lateral tilt (outward tilt)Lateral tilt (outward tilt)– during abduction during abduction – scapula rotates about its vertical axis resulting in scapula rotates about its vertical axis resulting in
posterior movement of medial border & anterior posterior movement of medial border & anterior movement of lateral bordermovement of lateral border
• Medial tilt (return from lateral tilt, inward tilt)Medial tilt (return from lateral tilt, inward tilt)– during extreme adductionduring extreme adduction– scapula rotates about its vertical axis resulting in scapula rotates about its vertical axis resulting in
anterior movement of medial border & posterior anterior movement of medial border & posterior movement of lateral bordermovement of lateral border
• Anterior tilt (upward tilt)Anterior tilt (upward tilt)– rotational movement of scapula about frontal axis rotational movement of scapula about frontal axis
occurring during glenohumeral hyperextensionoccurring during glenohumeral hyperextension– superior border moving anteroinferiorly & inferior superior border moving anteroinferiorly & inferior
• Posterior tilt (downward tilt)Posterior tilt (downward tilt)– rotational movement of scapula about frontal axis rotational movement of scapula about frontal axis
occurring during glenohumeral hyperflexionoccurring during glenohumeral hyperflexion– superior border moving posteroinferiorly & inferior superior border moving posteroinferiorly & inferior
• Synergy with muscles of glenohumeral jointSynergy with muscles of glenohumeral joint– As shoulder joint goes through more extreme As shoulder joint goes through more extreme
ranges of motion, scapular muscles contract to ranges of motion, scapular muscles contract to move shoulder girdle so that its glenoid fossa will move shoulder girdle so that its glenoid fossa will be in a more appropriate position from which the be in a more appropriate position from which the humerus can movehumerus can move
– Without the accompanying scapula movement Without the accompanying scapula movement humerus can only be raised into approximately 90 humerus can only be raised into approximately 90 degrees of total shoulder abduction & flexiondegrees of total shoulder abduction & flexion
• Synergy with muscles of glenohumeral jointSynergy with muscles of glenohumeral joint– This works through the appropriate muscles of This works through the appropriate muscles of
both joints working in synergy to accomplish the both joints working in synergy to accomplish the desired action of the entire upper extremitydesired action of the entire upper extremity
– Ex. to raise our hand out to the side laterally as Ex. to raise our hand out to the side laterally as high as possible, the serratus anterior & trapezius high as possible, the serratus anterior & trapezius (middle & lower fibers) muscles upwardly rotate (middle & lower fibers) muscles upwardly rotate scapula as supraspinatus & deltoid initiate scapula as supraspinatus & deltoid initiate glenohumeral abductionglenohumeral abduction
– This synergy between scapula & shoulder joint This synergy between scapula & shoulder joint muscles enhances movement of entire upper muscles enhances movement of entire upper extremityextremity
• 5 muscles primarily involved in 5 muscles primarily involved in shoulder girdle movementsshoulder girdle movements– All originate on axial skeleton & insert All originate on axial skeleton & insert
on scapula and/or clavicleon scapula and/or clavicle– Do not attach to humerus & do not Do not attach to humerus & do not
cause shoulder joint actionscause shoulder joint actions– Essential in providing dynamic stability Essential in providing dynamic stability
of the scapula so it can serve as a of the scapula so it can serve as a relative base of support for shoulder relative base of support for shoulder joint activities such as throwing, joint activities such as throwing, batting, & blockingbatting, & blocking
Rhomboid muscles - major & Rhomboid muscles - major & minorminor
Downward rotation: Downward rotation: from upward rotated from upward rotated position they draw position they draw scapula in scapula in downward rotationdownward rotation
Elevation: slight Elevation: slight upward movement upward movement accompanying accompanying adductionadduction
Rhomboid major & minor muscles Rhomboid major & minor muscles work togetherwork together
http://radlinux1.usuf1.usuhs.mil/rad/iong/index.html – This site has numerous radiological views of the musculoskeletal
system.University of Arkansas Medical School Gross Anatomy for Medical
Studentshttp://anatomy.uams.edu/anatomyhtml/grossresources.html– Dissections, anatomy tables, atlas images, links, etc.
Loyola University Medical Center: Structure of the Human Bodywww.meddean.luc.edu/lumen/MedEd/GrossAnatomy/GA.html– An excellent site with many slides, dissections, tutorials, etc., for the
study of human anatomyWheeless’ Textbook of Orthopaedics
www.wheelessonline.com/– This site has an extensive index of links to the fractures, joints,
muscles, nerves, trauma, medications, medical topics, lab tests, and links to orthopedic journals and other orthopedic and medical news.