14Large ROM Due To: Poor bony structure Poor ligamentous restraint Scapulohumeral cooperative action
15The Shoulder Complex General Structure & Function Structure & Function of Specific JointsMuscular ConsiderationsSpecific Functional ConsiderationsCommon Injuries
16Structure & Function of Specific Joints Sternoclavicular JointAcromioclavicular JointScapulothoracic JointGlenolhumeral JointCoracoacromial Arch
17Sternoclavicular Joint: Bony Structure PoorDiarthrodial BiaxialSternoclavicular 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 scapulaFreely permitted frontal and transverse plane motion.Allows some forward and backward sagittal plane rotation.Rotation
23Sternoclavicular Joint: Articular Surfaces Medial end of claviceis convexClavicular facet isreciprocally shapedLinks axial skeleton with appendicular skeleton. Thus, the SC joint is subjected to complex functional demnds. The saddle shaped articular surface provides stability.
25Sternoclavicular Joint: Motions Frontal planeElev/DepSagittal planePost RotHorizontal planeProT/ReTAnt/Post axisVertical axisElevation and depression in frontal plane, protraction and retraction in horizontal plane, posterior clavicular rotation in sagittal plane.
26Acromioclavicular Joint Bony Structure PoorDiarthrodial NonaxialIrregular diarthrodial joint between the acromion process of the scapula and the distal clavicle.allows limited motions in all three planes.Rotation occurs during arm elevationClose-packed position with humerus abducted to 90 degreesThere is a significant amount of anatomical variation in the AC joint from individual to individual, with some featuring an extra coracoclavicular facet.
27Acromioclavicular Joint: Joint Capsule Very weak
29Acromioclavicular Joint Coracoclavicular Ligament Resists superior motionA syndesmosis with coracoid process of scapulabound to the inferior clavicle by the coracoclavicular ligament.Permits little movement
31Acromioclavicular Joint: Motion Little relative motion at AC jointUR/DR: 60°EL/DEP: 30°PROT/RET: °
32Acromioclavicular Joint: Osteokinematics Horizontal planeadjustmentsduring scapulothoracicprotractionSagittal plane adjustmentelevationOsteokinematics 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.
33Clavicle Acts a strut connecting upper extremity to thorax Protects brachial plexus & vascular structuresServes as attachment site for many shoulder muscles
34Scapula Region between the anterior scapula and thoracic wall. Functions of muscles attaching to scapula:Contract to stabilize shoulder regionFacilitate 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 scapulaFacilitate 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.
36Scapulothoracic Joint Region between the anterior scapula and thoracic wall.Functions of muscles attaching to scapula:Contract to stabilize shoulder regionFacilitate 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 scapulaFacilitate 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 connectionSUBSCAP & SA
37Glenohumeral Joint: Humerus Retroversion angle: 30°Most freely moving joint in human bodyGlenoid Labrum composed of:Joint capsuleTendon of long head of biceps brachiiGlenohumeral ligamentsRotator CuffRotator Cuff MusclesMost 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 fossaGlenoid fossa less curved, there are anatomical variations in shape of glenoid fossa in people.45% population have an oval or egg shaped cavity55% 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 fossaGlenohumeral 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
47Glenohumeral Joint: Bursae SubcoracoidSubacromialSubscapularSmall fibrous sacs that secrete synovial fluid internally to lessen friction between soft tissues around joints.Shoulder contains:Subcoracoid bursaSubscapularis bursaSubacromial bursaSubacromial Bursa: in subacromial space, between process of scapula and coracoacromial ligament (above) and the glenohumeral joint (below)cushions rotator cuff musclescan become irritated when repeatedly compressed during overhead arm action.
48Glenohumeral Joint: Accessory Structures Labrum50% of depthIncreases tangential stability 20%
57Retraction of the Scapulothoracic Joint Levator scapulaCooperation of MT, LT, and rhomboids to retract ST joint. Notice combination of forces yielding single retraction force.
58Protraction of the Scapulothoracic Joint Pectoralis minor
59Pathomechanics 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
62GH Flexion Prime flexors: Assistant flexors: Anterior deltoid Pectoralis major: clavicular portionAssistant flexors:CoracobrachialisBiceps brachii: short headAlthough 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.
63GH Flexion Anterior deltoid Coracobrachialis Biceps brachii Elevation of the arm through flexion: anterior deltoid, coracobrachialis, and long head of biceps brachii.
64GH 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 flexorsResistance muscles: sternocostal pectoralis, latissimus dorsi, teres majorEffectiveness of biceps brachii increases with elbow in flexion.
65Abduction at Glenohumeral Joint Major abductors of humerus:SupraspinatusInitiates abductionActive for first 110 degrees of abductionMiddle deltoidActive degrees of abductionSuperior dislocating component neutralized by infraspinatus, subscapularis, and teres minorBoth 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
66Abduction at Glenohumeral Joint Initiates abductionActive for first 110 degrees of abductionActive degrees of abductionSuperior dislocating componentneutralized by infraspinatus, subscapularis, and teres minorBoth 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
67Abduction 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).
68Adduction of Glenohumeral Joint Primary adductors:Latissimus dorsiTeres majorSternocostal pectoralisMinor assistance:Biceps brachii: short headTriceps brachii: long headAbove 90 degrees- coracobrachialis and subscapularisPrimary adductors all located on inferior side of joint
69GH Medial Rotation Subscapularis Latissimus dorsi Pectoralis major Teres major (with resistance)Decreased activity with ABDSubscapularisHas greatest mechanical advantage for medial rotationMuscles 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.
70GH Lateral Rotation Primary Assistant: Infraspinatus Teres minor Posterior deltoidMuscles 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.
71Horizontal Adduction and Abduction Anterior to joint:Pectoralis major (both heads), anterior deltoid, coracobrachialisAssisted by short head of biceps brachiPosterior to joint:Middle and posterior deltoid, infraspinatus, teres minorAssisted by teres major, latissimus dorsiMuscles anterior to joint produce horizontal adductionMuscles posterior to joint produce horizontal abduction
72Muscle Strength Adduction (2X ABD) Extension Flexion Abduction Internal rotation (max in neutral)External rotation (max at 90° FL)Role of multiarticular muscles???
73The Shoulder Complex General Structure & Function Structure & Function of Specific JointsMuscular ConsiderationsSpecific Functional ConsiderationsCommon Injuries
74Specific Functional Considerations Stability Functions of Shoulder GirdleMobility Functions of Shoulder GirdleRotator Cuff Function
75Stability Functions of Shoulder Girdle Provides stable base from which shoulder muscles can generate forceShoulder girdle muscles as stabilizersMaintain appropriate force-length relationshipMaintain maximum congruence of shoulder joint
76Specific Functional Considerations Stability Functions of Shoulder GirdleMobility Functions of Shoulder GirdleRotator Cuff Function
77Mobility Functions of Shoulder Girdle Permits largest ROM of any complex in the bodyShoulder 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
78Dynamic Stabilization Mechanisms Passive muscle tensionCompressive forces from muscle contractionJoint motion that results in tightening of passive structuresRedirection of joint force toward center of GH jointWhen a segment or set of segments are more dependent on muscles than on joint structures for maintenance of integrity
79Muscular Considerations Force-length relationships quite variable due to multiple jointsTension development in agonist frequently requires tension development in antagonist to prevent dislocation of the humeral headForce couple – 2 forces equal in magnitude but opposite in direction
80Movements in the Frontal Plane GH Joint - Abduction UR - 20°Shoulder Girdle: URTotalsUpward rotation - 60°GH Abduction - 120°2:1 (.66) ratio1.25:1 after 30°across individualsABD - 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 jointalso: 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 humerusfirst 90 degrees of arm elevation, clavicle elevated approx of motion at sternoclavicular jointScapulohumeral 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 jointsPositioning further facilitated by motions of spineScapulohumeral RhythmFunctions:1) stabilize the scapula when shoulder complex is loaded2) move and position the scapula to facilitate movement at glenohumeral jointAre: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.ABD30°
81Movements in the Frontal Plane GH Joint - Adduction Shoulder Girdle: DRFig 5.17
82Movements in the Sagittal Plane GH Joint – Flexion & Extension Shoulder Girdle:URELEV (>90°)PROT ( to 90°)RET (>90°)Fig 5.18
83Movements in the Sagittal Plane GH Joint - Hyperextension Shoulder Girdle: Upward tilt of scapulaFig 5.20
84Movements in the Transverse Plane GH Joint – MR & LR Fig 5.22a
86Movements in the Transverse Plane GH HAdd & HAbd
87Influences 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 positionElbow position
88Large ROM Due To:Poor bony structurePoor ligamentous restraintScapulohumeral coordinationNormal movement dependent on interrelationships of 4 jointsRestriction in any of these four can impair normal function
89Specific Functional Considerations Stability Functions of Shoulder GirdleMobility Functions of Shoulder GirdleRotator Cuff Function
98Summary 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.
99Destabilizing Action of Latissimus Dorsi LD pulls humerus INFSSP resists INF forceINF & SUBSCAP create compressive force
100The Shoulder Complex General Structure & Function Structure & Function of Specific JointsMuscular ConsiderationsSpecific Functional ConsiderationsCommon Injuries
102Evaluation 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?
103Joint Dislocations: Acromioclavicular Sprain AKA Shoulder SeparationMOI: Downward blow to outer end of shoulderFall on outstretched hand, PunchingPATH: Sprain of AC ligamentsS&S: Pain over AC jointLaxity of AC joint???Acromion driven under the clavicleSC dislocation very uncommon – sternum driven over (anterior) the manubrium
104Joint Dislocations: Shoulder Dislocation MOI: Arm forcefully ABD & LRMay occur by a blow to top of shoulderPATH: Head of humerus is forced out of the glenoid fossaS&S: Arm held out from side in slight ABD & LRLoss of normal rounded contour of deltoid muscleDislocations: most commonly happens in glenohumeral joint. Typically occur when the humerus is abducted and externally rotatedpredisposition factors: inadequate glenoid fossa size, anterior tilt of glenoid fossa, inadequate retroversion of humeral head, deficits in rotator cuff musclesMost common anteriorly in contact sports
105Chronic Dislocation of the Shoulder MOI: Congenital abnormalityRepeated acute dislocationsPATH: Head of humerus relatively easily come out of the glenoid fossaTissue damage due to repeated dislocationsS&S: Usually not very painful
106Clavicular Fracture MOI: Downward blow to outer end of shoulder Fall on outstretched handPATH: Fracture to middle 1/3S&S: Patient supports injured armHead may be tilted toward injured side with face turned to opposite side
107Rotator Cuff Injuries MOI: Overuse Falling on an outstretched handPATH: Strains or tearing of rotator cuff musclesSupraspinatus most often injuredS&S: Pain, Inflammation, WeaknessUsually SSPRotator Cuff Damage: Rotator Cuff Impingement Syndromecaused by progressive pressure on rotator cuff tendons by by surrounding bone and soft tissuesSymptoms: hypomobility of posterior capsuleexcessive external rotation coupled with limited internal rotation of the humerusgeneral ligament laxity at glenohumeral jointImpingement 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
108Impingement Possible mechanisms Weak or inflexible rotator cuff Small anatomical spaceHyperabduction of GH jointGH ABD + ROTOccurs 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.
109Impingement: Roll-Slide Kinematics “Roll” created by abduction not countered with “Slide” actionAbduction without a concurrent inferior slide causes humeral head to “impinge” against arch. This prevents further abduction.
110Rotator Cuff Injury Anatomical cause of rotator cuff injury Kinesiological cause of injury
111Impingement Narrow space Inextensibility of capsule, ligaments, muscles – esp. rotator cuffAbduction and internal/external rotations
112During ABDSSP tendon pushed into acromion process & CA ligamentDuring ROTSSP tendon dragged along the inferior surface of the acromion process
113Rotator Cuff Injury Anatomical cause of rotator cuff injury Kinesiological cause of injury
114No excessive movements Kinesiological breakdown of overhand throwingWind-Up PhaseNo excessive movements(safe)First MotionMaximum knee lift of leg
115Abduction and no rotation Kinesiological breakdown of overhand throwingShoulder ABD (DELT & SSP)RC maintain proper humeral head positionStrideAbduction and no rotation(Safe)Lead leg begins to moveArms separateLead foot contacts the ground
116External rotation in abducted position Kinesiological breakdown of overhand throwingER in ABD position; ER °ECC action of SUBSCAP (decelerates ER humerus)RC stabilizationArm CockingExternal rotation in abducted positionPossible cuff damageLead foot contactMaximum shoulder external rotation
117Internal rotation in abducted position Kinesiological breakdown of overhand throwingArm AccelerationConcentric IR (PMJR & LD )IR velocity (> 1000 °/s)RC stabilizationInternal rotation in abducted positionPossible cuff damageMaximum shoulder ERBall release
118Internal rotation Abduction reduced Kinesiological breakdown of overhand throwingArm DecelerationDecelerating IR & ADDECC action of TMinRC stabilizationInternal rotation Abduction reducedSaferBall releaseMaximum shoulder IR
119Reduced internal rotation Kinesiological breakdown of overhand throwingFollow ThroughDecelerating IRECC action of TMinRC stabilizationReduced internal rotationSafeMaximum shoulder IREnds in balanced position
120Rotator Cuff Injuries: Solution Alter technique during problem phases to avoid impingementArm cockingArm accelerationStrengthen rotator cuffSurgical repairVideo techniques
121Risk FactorsRisk factor – a characteristic that influences the loading on the musculoskeletal systemMovement risk factors – characteristics of a movementIntrinsic risk factors – the personal, physical, and psychological characteristics of an individualExtrinsic risk factors – the environmental and administrative procedures
122Intrinsic Risk Factors Age and genderPhysical fitnessOvertrainingSkeletal abnormalitiesTechniqueWarm-upPsychological factorsAge and genderPhysical fitnessImbalances in strength & extensibilityGrowth-related imbalances in strength & extensibilityOvertrainingSkeletal abnormalitiesLeg length inequalityFemoral anteversionTibial varumTechniqueInappropriate utilization & summation of muscular effortAbnormal joint movementsWarm-upPsychological factors
123TechniqueTechnique 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.
124Swimming Solutions: Lead with hand to ↓ IR Increase body roll to ↓ ABD Mechanism: ABD + IR
126Other Rotational Injuries Tears of labrumMostly in anterior-superior regionTears of biceps brachii tendonDue to forceful rotational movementsAlso: calcification of soft tissues, degenerative changes in articular surfaces, bursitisForceful rotational movements include throwing, serving in tennis and spiking in volleyball.
128Subscapular Neuropathy Denervation of INF with ↓ strength GH ERMechanism: Repeated stretching of nerveSubscapular Neuropathy: condition involves denervation of infraspinatus, with accompanying loss of strength during external rotation of humerus. Due to repeated stretching of nerve during serving.
129Loads 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 flexionGlenohumeral 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.
130Injury Potential in the Shoulder Complex - Impacts Sternoclavicular Jointnot commonly injuredmay sprain anteriorly if fall on top of shoulder or middle delt - pain in horizontal abdchildren may dislocate anteriorly during throwing because of increased joint mobility as compared to adultsposterior dislocation may occur when force is applied to sternal end of clavicle; serious because of trachea, esophagus, and blood vessels located posteriorlyClavicular Injuriesfx to any part due to direct traumafx to middle 1/3 can occur by falling on shoulder, outstretched arm, or direct trauma to shoulder that transmits force down shaft of clavicleAC Injuriesdislocation from fall on shoulder, fall on elbow or outstretched armoveruse injuries from overhand pattern (throwing, tennis, swimming) or sports that repeatedly load in the overhead position (wrestling, wt lifting)
131Glenohumeral Injuries Most common dislocation in anterior (anterior-inferior 95%)most commonly dislocated when abducted and ER overheadrecurrence rate 33-50% (66-90% <20 yrs)