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The Shoulder Complex.

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1 The Shoulder Complex

2 The Shoulder Complex General Structure & Function
Structure & Function of Specific Joints Muscular Considerations Specific Functional Considerations Common Injuries

3 The Shoulder Complex General Structure & Function
Structure & Function of Specific Joints Muscular Considerations Specific Functional Considerations Common Injuries

4 General Structure gross structure includes the scapulae, clavicles, humerus, and the joints that link these bones together

5 General Function Provides very mobile, yet strong base for hand to perform its intricate gross and skilled functions Transmits loads from upper extremity to axial skeleton

6 Shoulder Girdle

7 Shoulder Complex Movements
Shoulder Girdle Elevation & depression Protraction & retraction Upward & downward rotation Upward tilt Shoulder (glenohumeral) FL, EXT, HyperEXT ABD, ADD, HyperADD, HyperABD MR, LR, HorizontalABD, HorizontalADD

8 Abduction/Lateral Tilt (Protraction)
Linear Movement Frontal Plane Angular movement Transverse Plane Adduction/Reduced Lateral Tilt (Retraction)

9 Depression Elevation Linear Movement Frontal Plane

10 Downward rotation Upward rotation

11 Shoulder Complex Movements
Upward tilt Reduction of Upward Tilt Angular movement Sagittal plane

12 Limited by capsular torsion
Limited by bony impingement of greater tubercle on acromion

13

14 Large ROM Due To: Poor bony structure Poor ligamentous restraint
Scapulohumeral cooperative action

15 The Shoulder Complex General Structure & Function
Structure & Function of Specific Joints Muscular Considerations Specific Functional Considerations Common Injuries

16 Structure & Function of Specific Joints
Sternoclavicular Joint Acromioclavicular Joint Scapulothoracic Joint Glenolhumeral Joint Coracoacromial Arch

17 Sternoclavicular Joint: Bony Structure
Poor Diarthrodial Biaxial Sternoclavicular Joint: modified ball and socket joint between the proximal clavicle and the manubrium of the sternum. Rotation: occurs during shrugging shoulders, elevating arms above head, swimming, etc. In close-packed position during maximal shoulder elevation. Provides major axis of rotation for movement of clavicle and scapula Freely permitted frontal and transverse plane motion. Allows some forward and backward sagittal plane rotation. Rotation

18 Sternoclavicular Joint: Capsule
Very strong

19 Sternoclavicular Joint: Interclavicular Ligament
Resists superior & anterior (posterior portion) motion

20 Sternoclavicular Joint: Sternoclavicular Ligament
Resists anterior (PSL), posterior (ASL), & superior motion

21 Sternoclavicular Joint: Costoclavicular Ligament
Resists upward and posterior motion

22 Sternoclavicular Joint: Accessory Structures
Resists medial & inferior displacement via articular contact

23 Sternoclavicular Joint: Articular Surfaces
Medial end of clavice is convex Clavicular facet is reciprocally shaped Links axial skeleton with appendicular skeleton. Thus, the SC joint is subjected to complex functional demnds. The saddle shaped articular surface provides stability.

24 Sternoclavicular Joint: Motions
Axial Rotation: 50° EL/DEP: 35° PROT/RET: 35°

25 Sternoclavicular Joint: Motions
Frontal plane Elev/Dep Sagittal plane Post Rot Horizontal plane ProT/ReT Ant/Post axis Vertical axis Elevation and depression in frontal plane, protraction and retraction in horizontal plane, posterior clavicular rotation in sagittal plane.

26 Acromioclavicular Joint Bony Structure
Poor Diarthrodial Nonaxial Irregular diarthrodial joint between the acromion process of the scapula and the distal clavicle. allows limited motions in all three planes. Rotation occurs during arm elevation Close-packed position with humerus abducted to 90 degrees There is a significant amount of anatomical variation in the AC joint from individual to individual, with some featuring an extra coracoclavicular facet.

27 Acromioclavicular Joint: Joint Capsule
Very weak

28 Acromioclavicular Joint Acromioclavicular Ligament
Resists axial rotation & posterior motion

29 Acromioclavicular Joint Coracoclavicular Ligament
Resists superior motion A syndesmosis with coracoid process of scapula bound to the inferior clavicle by the coracoclavicular ligament. Permits little movement

30 Acromioclavicular Joint Accessory Structures
Articular disc

31 Acromioclavicular Joint: Motion
Little relative motion at AC joint UR/DR: 60° EL/DEP: 30° PROT/RET: °

32 Acromioclavicular Joint: Osteokinematics
Horizontal plane adjustments during scapulothoracic protraction Sagittal plane adjustment elevation Osteokinematics of right acromioclavicular joint. Primary motions are upward and downward rotation. Note inclusion of horizontal and sagittal plane adjustments (secondary motions). Horizontal plane adjustments at AC joint occur about a vertical axis, which causes medial border of scapula to pivot away thorax. Sagittal plane adjustments occur about a medial/lateral axis, causing inferior angle to tilt away or toward thorax.

33 Clavicle Acts a strut connecting upper extremity to thorax
Protects brachial plexus & vascular structures Serves as attachment site for many shoulder muscles

34 Scapula Region between the anterior scapula and thoracic wall.
Functions of muscles attaching to scapula: Contract to stabilize shoulder region Facilitate movements of the upper extremity through appropriate positioning of the glenohumeral joint. Contract to….example: lifting something from the floor, the levator scapula, trapezius, and rhomboids develop tension to support scapula Facilitate movements…example: during overhand throw, rhomboids contract to move the entire shoulder posteriorly as humerus is horizontally abducted and externally rotated during preparatory phase. As the arm and hand move forward, to execute the throw, tension in the rhomboids is released to permit forward movement of the glenohumeral joint.

35 Scapular Plane

36 Scapulothoracic Joint
Region between the anterior scapula and thoracic wall. Functions of muscles attaching to scapula: Contract to stabilize shoulder region Facilitate movements of the upper extremity through appropriate positioning of the glenohumeral joint. Contract to….example: lifting something from the floor, the levator scapula, trapezius, and rhomboids develop tension to support scapula Facilitate movements…example: during overhand throw, rhomboids contract to move the entire shoulder posteriorly as humerus is horizontally abducted and externally rotated during preparatory phase. As the arm and hand move forward, to execute the throw, tension in the rhomboids is released to permit forward movement of the glenohumeral joint. No osseous connection SUBSCAP & SA

37 Glenohumeral Joint: Humerus
Retroversion angle: 30° Most freely moving joint in human body Glenoid Labrum composed of: Joint capsule Tendon of long head of biceps brachii Glenohumeral ligaments Rotator Cuff Rotator Cuff Muscles Most stable in close-packed position, when the humerus is abducted and laterally rotated. Glenohumeral Joint: ball and socket joint in which the head of the humerus articulates with the glenoid fossa of the scapula. Allows for flexion, extension, hyperextension, abduction, adduction, horizontal abduction and adduction, medial and lateral rotation of the humerus. Head of humerus has 3-4 times the surface area of shallow glenoid fossa Glenoid fossa less curved, there are anatomical variations in shape of glenoid fossa in people. 45% population have an oval or egg shaped cavity 55% population have pear shaped cavity. Glenoid Labrum: rim of soft tissue located on the periphery of the glenoid fossa that adds stability to the glenohumeral joint through deepening the fossa Glenohumeral Ligaments: are: superior, middle, and inferior and all merge with glenohumeral joint capsule on anterior side and coracohumeral ligament on superior side. Rotator Cuff: band of tendons of subscapularis, supraspinatus, infraspinatus, and teres minor, which attach to the humeral head. Surrounds shoulder on posterior, superior and anterior sides. Tension here pulls the head of the humerus toward the glenoid fossa, contributing to joint’s minimal stability. Rotator Cuff Muscles: subscapularis, supraspinatus, infraspinatus, and teres minor

38 Glenohumeral Joint: Humerus
Inclination angle: 45°

39 Glenohumeral Joint: Glenoid Fossa
Inclination angle: 5° Retroversion angle: 7° Provides better stability & congruency with humeral head

40 Glenohumeral Joint: Glenoid Fossa
Articular cartilage thicker on periphery Shallow fossa 1/3 diameter of humeral head Provides better stability & congruency with humeral head

41 Glenohumeral Joint: Bony Structure
Pure rotation Bony restraint poor Head 4-5X larger than fossa Close-packed position ABD with LR

42 Glenohumeral Joint: Joint Capsule
Inherently lax Surface area 2X head Provides restraint for ABD, ADD, LR, MR

43 Glenohumeral Joint: Superior GH Ligament
Resists inferior translation in rest or adducted arm Well-developed in 50%

44 Glenohumeral Joint: Coracohumeral Ligament
Resists inferior translation in shoulders with less-developed SGH

45 Glenohumeral Joint: Middle GH Ligament
Great variability in proximal attachment & morphology Absent in 30% Resists inferior translation in ABD & ER Restrains anterior translation (45° ABD)

46 Glenohumeral Joint: Inferior GH Ligament
3 components (A,P,Ax) Resists inferior, anterior, & posterior translation

47 Glenohumeral Joint: Bursae
Subcoracoid Subacromial Subscapular Small fibrous sacs that secrete synovial fluid internally to lessen friction between soft tissues around joints. Shoulder contains: Subcoracoid bursa Subscapularis bursa Subacromial bursa Subacromial Bursa: in subacromial space, between process of scapula and coracoacromial ligament (above) and the glenohumeral joint (below) cushions rotator cuff muscles can become irritated when repeatedly compressed during overhead arm action.

48 Glenohumeral Joint: Accessory Structures
Labrum 50% of depth Increases tangential stability 20%

49 Glenohumeral Joint: Intra-articular Pressure
Synovial fluid causes adhesion Provides ~50% restraint

50 Coracoacromial Arch

51 Glenohumeral Joint: ROM
Flexion (167° W; 171° M) 30° in max LR Extension (60°) Abduction (180°) 60° in max IR Hyperadduction (75°)

52 Glenohumeral Joint: ROM
Total rotation 180° Total ROT 90° in 90° ABD Medial rotation (90°) Lateral rotation (90°) Horizontal abduction (45°) Horizontal adduction (135°) Role of multiarticular muscles???

53 Glenohumeral Joint: ROM
Medial rotation (90°) Lateral rotation (90°) Horizontal abduction (45°) Horizontal adduction (135°)

54 Soft Tissue Restraint Summary
Anterior Capsule Labrum Glenohumeral lig Coracohumeral lig Subscapularis Pectoralis major Inferior Triceps brachii (L) Posterior Capsule Labrum Teres minor Infraspinatus Superior Coracohumeral lig Suprapinatus Biceps brachii (L) Coracoacromial arch Subacromial bursa

55 The Shoulder Complex General Structure & Function
Structure & Function of Specific Joints Muscular Considerations Specific Functional Considerations Common Injuries

56 Shoulder girdle has its own set of muscles.

57 Retraction of the Scapulothoracic Joint
Levator scapula Cooperation of MT, LT, and rhomboids to retract ST joint. Notice combination of forces yielding single retraction force.

58 Protraction of the Scapulothoracic Joint
Pectoralis minor

59 Pathomechanics of a weak serratus anterior muscle
Deltoid force causes scapula to downwardly rotate. Weak serratus anterior m. cannot provide adequate upward rotation force. Scapula cannot resist pull of deltoid. Result is “winging” of the scapula. Unstable and cannot resist deltoid force

60

61

62 GH Flexion Prime flexors: Assistant flexors: Anterior deltoid
Pectoralis major: clavicular portion Assistant flexors: Coracobrachialis Biceps brachii: short head Although the long head of the biceps also crosses the shoulder, it is not active in isolated shoulder motion when the elbow and forearm do not move.

63 GH Flexion Anterior deltoid Coracobrachialis Biceps brachii
Elevation of the arm through flexion: anterior deltoid, coracobrachialis, and long head of biceps brachii.

64 GH Extension Gravitational force Posterior deltoid Latissimus dorsi
Pectoralis major (sternal) Teres major (with resistance) Gravitational force is primary mover when shoulder extension isn’t resisted. Control by eccentric contraction of flexors Resistance muscles: sternocostal pectoralis, latissimus dorsi, teres major Effectiveness of biceps brachii increases with elbow in flexion.

65 Abduction at Glenohumeral Joint
Major abductors of humerus: Supraspinatus Initiates abduction Active for first 110 degrees of abduction Middle deltoid Active degrees of abduction Superior dislocating component neutralized by infraspinatus, subscapularis, and teres minor Both muscles cross the shoulder superior to the glenohumeral joint. Prime movers that abduct GH joint are the anterior deltoid, the middle deltoid, and the supraspinatus muscles

66 Abduction at Glenohumeral Joint
Initiates abduction Active for first 110 degrees of abduction Active degrees of abduction Superior dislocating componentneutralized by infraspinatus, subscapularis, and teres minor Both muscles cross the shoulder superior to the glenohumeral joint. Prime movers that abduct GH joint are the anterior deltoid, the middle deltoid, and the supraspinatus muscles

67 Abduction at Glenohumeral Joint: The “Kinetic Arc”
“Shoulder abduction requires a muscular “kinetic arc” between the humerus and axial skeleton”. Figure shows muscular interaction between the scapulothoracic upward rotators and GH abductors (Neuman, 2002).

68 Adduction of Glenohumeral Joint
Primary adductors: Latissimus dorsi Teres major Sternocostal pectoralis Minor assistance: Biceps brachii: short head Triceps brachii: long head Above 90 degrees- coracobrachialis and subscapularis Primary adductors all located on inferior side of joint

69 GH Medial Rotation Subscapularis Latissimus dorsi Pectoralis major
Teres major (with resistance) Decreased activity with ABD Subscapularis Has greatest mechanical advantage for medial rotation Muscles attaching to the posterior aspect of the humerus, particularly infraspinatus and teres minor, produce lateral or outward rotation, with some assistance from the posterior deltoid.

70 GH Lateral Rotation Primary Assistant: Infraspinatus Teres minor
Posterior deltoid Muscles attaching to the posterior aspect of the humerus, particularly infraspinatus and teres minor, produce lateral or outward rotation, with some assistance from the posterior deltoid.

71 Horizontal Adduction and Abduction
Anterior to joint: Pectoralis major (both heads), anterior deltoid, coracobrachialis Assisted by short head of biceps brachi Posterior to joint: Middle and posterior deltoid, infraspinatus, teres minor Assisted by teres major, latissimus dorsi Muscles anterior to joint produce horizontal adduction Muscles posterior to joint produce horizontal abduction

72 Muscle Strength Adduction (2X ABD) Extension Flexion Abduction
Internal rotation (max in neutral) External rotation (max at 90° FL) Role of multiarticular muscles???

73 The Shoulder Complex General Structure & Function
Structure & Function of Specific Joints Muscular Considerations Specific Functional Considerations Common Injuries

74 Specific Functional Considerations
Stability Functions of Shoulder Girdle Mobility Functions of Shoulder Girdle Rotator Cuff Function

75 Stability Functions of Shoulder Girdle
Provides stable base from which shoulder muscles can generate force Shoulder girdle muscles as stabilizers Maintain appropriate force-length relationship Maintain maximum congruence of shoulder joint

76 Specific Functional Considerations
Stability Functions of Shoulder Girdle Mobility Functions of Shoulder Girdle Rotator Cuff Function

77 Mobility Functions of Shoulder Girdle
Permits largest ROM of any complex in the body Shoulder girdle increases ROM with less compromise of stability (scapulohumeral rhythm) (4 joints vs. 1 joint) Facilitate movements of the upper extremity by positioning GH favorably

78 Dynamic Stabilization Mechanisms
Passive muscle tension Compressive forces from muscle contraction Joint motion that results in tightening of passive structures Redirection of joint force toward center of GH joint When a segment or set of segments are more dependent on muscles than on joint structures for maintenance of integrity

79 Muscular Considerations
Force-length relationships quite variable due to multiple joints Tension development in agonist frequently requires tension development in antagonist to prevent dislocation of the humeral head Force couple – 2 forces equal in magnitude but opposite in direction

80 Movements in the Frontal Plane GH Joint - Abduction
UR - 20° Shoulder Girdle: UR Totals Upward rotation - 60° GH Abduction - 120° 2:1 (.66) ratio 1.25:1 after 30° across individuals ABD - 30° UR - 40° GH abduction is essential feature of many overhead arm actions such as reaching up to a high shelf, changing a bulb in a ceiling light, putting on your hat, washing and combing your hair, pitching a baseball, throwing a football, serving in tennis, throwing a javelin, spiking and blocking a volleyball, bowling in cricket, and all of the major swimming strokes. Pattern among all individuals: first 30 degrees of humeral elevation, scapula contributes 1/5 of glenohumeral joint also: rotation occurs at the acromioclavicular joint (again: at 135 degrees to max. elevation) beyond 30 degrees: scapula rotates approximately 1 degree for every 2 degrees of movement of humerus first 90 degrees of arm elevation, clavicle elevated approx of motion at sternoclavicular joint Scapulohumeral Rhythm: a regular pattern of scapular rotation that accompanies and facilitates humeral abduction. enables greater ROM at shoulder than if it were fixed. altered with the orientation of the scapula when hands support external load. Humerus movement usually involves some movement at all three shoulder joints Positioning further facilitated by motions of spine Scapulohumeral Rhythm Functions: 1) stabilize the scapula when shoulder complex is loaded 2) move and position the scapula to facilitate movement at glenohumeral joint Are: Levator scapula, rhomboids, serratus anterior, pectoralis minor, subclavius, and four parts to trapezius. Many muscles involved, some contribute more than others. At 100 deg, costoclavicular ligament becomes taut and prevents further upward rotation of clavicle about the SC joint. Last 80 deg involves shoulder ABD, UR of scapula about 20 deg (limited by coracoclavicular ligaments), and axial rotation of clavicle (CCW with respect to right clavicle when viewed from a lateral aspect). The other 60 deg occurs through the GH ABD, clavicular axial rotation, and scapulothoracic movement. Also accompanied by ER of humerus to maintain articular contact and prevent impingement of greater tubercle on coracoacromial arch. ABD 30°

81 Movements in the Frontal Plane GH Joint - Adduction
Shoulder Girdle: DR Fig 5.17

82 Movements in the Sagittal Plane GH Joint – Flexion & Extension
Shoulder Girdle: UR ELEV (>90°) PROT ( to 90°) RET (>90°) Fig 5.18

83 Movements in the Sagittal Plane GH Joint - Hyperextension
Shoulder Girdle: Upward tilt of scapula Fig 5.20

84 Movements in the Transverse Plane GH Joint – MR & LR
Fig 5.22a

85 Spinal Contribution to GH Motion

86 Movements in the Transverse Plane GH HAdd & HAbd

87 Influences on GH ROM Humeral position in other planes
FL limited by ER (30 FL in max ER) ABD limited by IR (60-90 ABD in max IR) ABD with ER =  Rotation limited by ABD (total ROT only 90 in 90 ABD) Scapular position Elbow position

88 Large ROM Due To: Poor bony structure Poor ligamentous restraint Scapulohumeral coordination Normal movement dependent on interrelationships of 4 joints Restriction in any of these four can impair normal function

89 Specific Functional Considerations
Stability Functions of Shoulder Girdle Mobility Functions of Shoulder Girdle Rotator Cuff Function

90 Teres minor Supraspinatus Subscapularis Infraspinatus

91

92 Function of Rotator Cuff
Large external muscles (e.g., lats, delts) create shear forces Rotator cuff provides Joint compression Tangential restraint (Ant, Post, Sup)

93 Destabilizing Action of Deltoid

94 Deltoid produces superior shear force at GH joint.

95 Subscapularis Resists superior shear
Produces simultaneous internal rotation

96 Infraspinatus & Teres Minor
Resists superior shear Neutralizes SUBSCAP internal rotation

97 Supraspinatus

98 Summary of Active Arthrokinematics Resisting Shear
Deltoid rolls humeral head upward. SupraS rolls humeral head into abduction…compressing the joint for added stability. Subscap, InfraS, TM exert downward translational force on the humeral head to resist excessive superior translation.

99 Destabilizing Action of Latissimus Dorsi
LD pulls humerus INF SSP resists INF force INF & SUBSCAP create compressive force

100 The Shoulder Complex General Structure & Function
Structure & Function of Specific Joints Muscular Considerations Specific Functional Considerations Common Injuries

101 Common Shoulder Injuries
Joint dislocations Clavicular fracture Rotator cuff injuries Other rotational injuries Subscapular neuropathy

102 Evaluation of Injuries
Mechanism of Injury (MOI): How did the injury occur? Pathology (PATH): What tissues are damaged? Sign & Symptoms (S&S): What does the patient tell you? What can be determined from an evaluation of the injury?

103 Joint Dislocations: Acromioclavicular Sprain
AKA Shoulder Separation MOI: Downward blow to outer end of shoulder Fall on outstretched hand, Punching PATH: Sprain of AC ligaments S&S: Pain over AC joint Laxity of AC joint??? Acromion driven under the clavicle SC dislocation very uncommon – sternum driven over (anterior) the manubrium

104 Joint Dislocations: Shoulder Dislocation
MOI: Arm forcefully ABD & LR May occur by a blow to top of shoulder PATH: Head of humerus is forced out of the glenoid fossa S&S: Arm held out from side in slight ABD & LR Loss of normal rounded contour of deltoid muscle Dislocations: most commonly happens in glenohumeral joint. Typically occur when the humerus is abducted and externally rotated predisposition factors: inadequate glenoid fossa size, anterior tilt of glenoid fossa, inadequate retroversion of humeral head, deficits in rotator cuff muscles Most common anteriorly in contact sports

105 Chronic Dislocation of the Shoulder
MOI: Congenital abnormality Repeated acute dislocations PATH: Head of humerus relatively easily come out of the glenoid fossa Tissue damage due to repeated dislocations S&S: Usually not very painful

106 Clavicular Fracture MOI: Downward blow to outer end of shoulder
Fall on outstretched hand PATH: Fracture to middle 1/3 S&S: Patient supports injured arm Head may be tilted toward injured side with face turned to opposite side

107 Rotator Cuff Injuries MOI: Overuse
Falling on an outstretched hand PATH: Strains or tearing of rotator cuff muscles Supraspinatus most often injured S&S: Pain, Inflammation, Weakness Usually SSP Rotator Cuff Damage: Rotator Cuff Impingement Syndrome caused by progressive pressure on rotator cuff tendons by by surrounding bone and soft tissues Symptoms: hypomobility of posterior capsule excessive external rotation coupled with limited internal rotation of the humerus general ligament laxity at glenohumeral joint Impingement Theory: suggest that narrow space between acromion process of scapula and the head of the humerus. Another theory states that inflammation of the supraspinatus tendon caused by repeated overstretching of muscle-tendon unit. Common among swimmers

108 Impingement Possible mechanisms Weak or inflexible rotator cuff
Small anatomical space Hyperabduction of GH joint GH ABD + ROT Occurs due to lack of flexibility in ligaments at any one of the 4 joints, but more likely to occur due to lack of extensibility in muscles, particularly those associated with the scapulothoracic mechanism. When the flexibility in the SC, AC, or ST joints is limited, the GH joint must hyperabduct to achieve full abduction of the arm. This hyperabduction at the GH joint can cause impingement.

109 Impingement: Roll-Slide Kinematics
“Roll” created by abduction not countered with “Slide” action Abduction without a concurrent inferior slide causes humeral head to “impinge” against arch. This prevents further abduction.

110 Rotator Cuff Injury Anatomical cause of rotator cuff injury
Kinesiological cause of injury

111 Impingement Narrow space
Inextensibility of capsule, ligaments, muscles – esp. rotator cuff Abduction and internal/external rotations

112 During ABD SSP tendon pushed into acromion process & CA ligament During ROT SSP tendon dragged along the inferior surface of the acromion process

113 Rotator Cuff Injury Anatomical cause of rotator cuff injury
Kinesiological cause of injury

114 No excessive movements
Kinesiological breakdown of overhand throwing Wind-Up Phase No excessive movements (safe) First Motion Maximum knee lift of leg

115 Abduction and no rotation
Kinesiological breakdown of overhand throwing Shoulder ABD (DELT & SSP) RC maintain proper humeral head position Stride Abduction and no rotation (Safe) Lead leg begins to move Arms separate Lead foot contacts the ground

116 External rotation in abducted position
Kinesiological breakdown of overhand throwing ER in ABD position; ER ° ECC action of SUBSCAP (decelerates ER humerus) RC stabilization Arm Cocking External rotation in abducted position Possible cuff damage Lead foot contact Maximum shoulder external rotation

117 Internal rotation in abducted position
Kinesiological breakdown of overhand throwing Arm Acceleration Concentric IR (PMJR & LD ) IR velocity (> 1000 °/s) RC stabilization Internal rotation in abducted position Possible cuff damage Maximum shoulder ER Ball release

118 Internal rotation Abduction reduced
Kinesiological breakdown of overhand throwing Arm Deceleration Decelerating IR & ADD ECC action of TMin RC stabilization Internal rotation Abduction reduced Safer Ball release Maximum shoulder IR

119 Reduced internal rotation
Kinesiological breakdown of overhand throwing Follow Through Decelerating IR ECC action of TMin RC stabilization Reduced internal rotation Safe Maximum shoulder IR Ends in balanced position

120 Rotator Cuff Injuries: Solution
Alter technique during problem phases to avoid impingement Arm cocking Arm acceleration Strengthen rotator cuff Surgical repair Video techniques

121 Risk Factors Risk factor – a characteristic that influences the loading on the musculoskeletal system Movement risk factors – characteristics of a movement Intrinsic risk factors – the personal, physical, and psychological characteristics of an individual Extrinsic risk factors – the environmental and administrative procedures

122 Intrinsic Risk Factors
Age and gender Physical fitness Overtraining Skeletal abnormalities Technique Warm-up Psychological factors Age and gender Physical fitness Imbalances in strength & extensibility Growth-related imbalances in strength & extensibility Overtraining Skeletal abnormalities Leg length inequality Femoral anteversion Tibial varum Technique Inappropriate utilization & summation of muscular effort Abnormal joint movements Warm-up Psychological factors

123 Technique Technique refers to the movement pattern of an individual during a particular movement or sequence of movements. Good technique is a movement pattern not only effective in performance, but also one that minimizes risk of injury by appropriately distributing the overall load throughout the kinetic chain. Poor technique is characterized by inappropriate utilization and summation of muscular effort and abnormal joint movements, both of which result in localized overload and, therefore, increased risk of injury.

124 Swimming Solutions: Lead with hand to ↓ IR Increase body roll to ↓ ABD
Mechanism: ABD + IR

125 Supraspinatus Tear

126 Other Rotational Injuries
Tears of labrum Mostly in anterior-superior region Tears of biceps brachii tendon Due to forceful rotational movements Also: calcification of soft tissues, degenerative changes in articular surfaces, bursitis Forceful rotational movements include throwing, serving in tennis and spiking in volleyball.

127 Biceps Tendon Tear

128 Subscapular Neuropathy
Denervation of INF with ↓ strength GH ER Mechanism: Repeated stretching of nerve Subscapular Neuropathy: condition involves denervation of infraspinatus, with accompanying loss of strength during external rotation of humerus. Due to repeated stretching of nerve during serving.

129 Loads on the Shoulder Arm segment moment arm:
Perpendicular distance between weight vector and shoulder. With elbow flexion, upper arm and forearm/hand segments must be analyzed separately. Large torques from extended moment arms countered by shoulder muscles. Load reduced by half with maximal elbow flexion Glenohumeral joint provides direct mechanical support for the arm, sustains greater loads than the other shoulder joints. Maximum shear force has been found to be present at the glenohumeral joint when the arm is elevated approximately 60 degrees.

130 Injury Potential in the Shoulder Complex - Impacts
Sternoclavicular Joint not commonly injured may sprain anteriorly if fall on top of shoulder or middle delt - pain in horizontal abd children may dislocate anteriorly during throwing because of increased joint mobility as compared to adults posterior dislocation may occur when force is applied to sternal end of clavicle; serious because of trachea, esophagus, and blood vessels located posteriorly Clavicular Injuries fx to any part due to direct trauma fx to middle 1/3 can occur by falling on shoulder, outstretched arm, or direct trauma to shoulder that transmits force down shaft of clavicle AC Injuries dislocation from fall on shoulder, fall on elbow or outstretched arm overuse injuries from overhand pattern (throwing, tennis, swimming) or sports that repeatedly load in the overhead position (wrestling, wt lifting)

131 Glenohumeral Injuries
Most common dislocation in anterior (anterior-inferior 95%) most commonly dislocated when abducted and ER overhead recurrence rate 33-50% (66-90% <20 yrs)


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