anatomy of shoulder joint

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ANATOMY OF SHOULDER JOINT

PRESENTOR:DR.VISHAL PUSHKARNA (FIRST YEAR PG ORTHOPAeDICS)MODERATOR: Dr.VAMSHI ASST.PROFESSOR,PIMSV.P

INTRODUCTIONShoulder joint is formed by scapula and clavicle (which is also called as shoulder girdle)and proximal humerus.It has the greatest range of motion of any joint in the body.Due to wide range of movement it is also most unstable joint compared to other joints of the body.However a series of complex ligaments and muscle keep it in jointV.P

BONES OF SHOULDER JOINT

Articulates at one end with the sternum (chest bone) and with the acromion of the scapula at the other.(Roof of the shoulder) Forms the front portion of the shoulder girdle and is palpable along its entire length with a gentle S-shaped contour.ClavicleV.P

It is a flat, triangular bone that lies over the back of the upper ribs. It serves as an attachment for some of the muscles and tendons of the arm, neck, chest and back and aids in the movements of the arm and shoulder.Anterior View

Posterior ViewScapulaV.P

The proximal humerus consists of the head, neck, greater and lesser tubercles, and the shaft. The neck lies between the head and the greater and lesser tubercles. The greater and lesser tubercles are prominent landmarks on the humerus and serve as attachment sites for the rotator cuff muscles. Proximal HumerusV.P

OSSIFICATION CENTRESV.P

CLAVICLEIts the 1st bone to ossify .It has no medullary cavity.It occurs by intramembranous ossification.Secondary ossification centres via endochondral.Medial epiphysis ossifies at 12-19yrs and fuses at 22 to 25yrs.Lateral epiphysis ossifies and fuses at 19yrs.

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SCAPULABody and spine[posterior] ossify at birthCoracoid process[anterior]-atavastic epiphysis. centre at 1yr,base at 10yrs.

Acromian[lateral projection]-fuses by 22yrs via 2- 5centres form at puberty

Glenoid-upper 1/4th ossify at 10yrs lower3/4th appear at puberty ,fuse by 22yrs

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PROXIMAL HUMERUSHumeral head-ossifies at 6mths

Greater tuberosity-ossifies at 1 to 3yrs

Lesser tuberosity-ossifies at 4 to 5yrs.

Physis close at 14-17yrs girls and 16-18yrs boys.

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Joints of the Shoulder Complex

Glenohumeral

Acromioclavicular

Sternoclavicular

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Glenohumeral

The glenohumeral joint is the most mobile joint in the body. The socket (glenoidfossa) is very shallow, and doesnt hold on to the ball (humeral head) very wellJoint type: ball and socket synovial joint It is therefore up to a group of muscles (called the Rotator Cuff - further discussed in the Muscles section) to hold the ball in the socket, providing stability and some movement V.P

The glenoid labrum also helps to improve the stability of the shoulder. The glenoid labrum is a cartilage ring around the glenoidfossa. This labrum makes the socket deeper, giving it a larger and deeper contact surface to articulate with the head of the humerus.

The articular capsule is a fibrous bag of tissue, fused with local ligaments, which provides a sealed sac around the glenohumeral joint.V.P

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Glenohumeral ligaments

provide anterior stability to the glenohumeral joint

Superior (SGHL)Middle (MGHL)Inferior (IGHL)

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Glenohumeral Joint

Superior GH LigamentResists inferior translation in rest or adducted armWell-developed in 50%

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Glenohumeral Joint

Middle GH LigamentGreat variability in proximal attachment & morphologyAbsent in 30%Resists inferior translation in ABD & ERRestrains anterior translation (45 ABD)

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Glenohumeral Joint

Inferior GH Ligament3 components (A,P,Ax)Resists inferior, anterior, & posterior translation

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CORACOHUMERAL LIGAMENTArises from lateral base of coracoid process and extends onto both tuberosities.It forms roof of bicipital tendon sheath and strengtens capsule anteriorly.Importance-resists inferior and posterior translation.

TRANSVERSE HUMERAL LIGAMENTBridges upper part of bicipital groove through which long head of biceps passes down.V.P

Joint type: plane or sliding synovial jointBones involved in the articulation:Acromion of the ScapulaDistal end of the ClavicleMovements: only small translationsAnterior/Posterior glideSuperior/Inferior tiltRotationAcromioclavicular JointV.P

Acromioclavicular ligament acts to secure the acromion and clavicle and provides a complete capsule around the joint.Coracoclavicular ligaments anchor the lateral aspect of the clavicle to the coracoid process of scapula. It consists of two small ligaments holding the scapula laterally, these are:

Trapeziod - attaches to the trapezoid line on the inferior surface of the clavicle

Conoid - attaches to the conoid tubercle of the clavicle

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Sternoclavicular JointV.P

Joint type: saddle synovial joint

Sternoclavicular JointBones involved in the articulation:Manubrium of the SternumProximal end of the ClavicleMovements:Anterior/Posterior glideSuperior/Inferior tiltRotationV.P

Take note of the:Sternoclavicular ligamentCostoclavicular and Interclavicular ligaments

Sternoclavicular Joint

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Scapulothoracic Joint

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Joint type: not a true joint, but known as a pseudo joint

Bones involved in the articulation:Anterior surface of the ScapulaRibcage of the Thorax

Scapulothoracic JointV.P

Movements:

Protraction and retractionElevation and depressionAnterior tilt and posterior tiltUpward rotation and downward rotation

As there is minimal bony contact, it is up to the muscles attaching to the scapula and thorax to stabilise and control movement at this articulation There is no joint capsule or synovial fluidScapulothoracic JointV.P

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The muscles of the shoulder girdle provide vital stability for the mobile shoulder joint

Muscles of the Shoulder

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Muscles - Trapezius

NameOriginInsertionActionInnervationTrapezius (upper, middle & lower)External occipital protuberance, ligamentumnuchae&spinous processes of C7-T12Lateral 1/3of clavicle, acromion& superior edge of the crest of the spine of the scapulaScapular stabilisationUpper scap elevationMiddle scap retractionLower - scap retractionAccessory nerv (XI) C3, 4

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Muscles - DeltoidNameOriginInsertionActionInnervationDeltoid (anterior, middle & posterior parts)Lateral 1/3 of clavicle, acromion process + spine of scapulaDeltoid tuberosityShoulder abduction Axillary nerve

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Muscles Levator ScapulaeLevator scapulaeTransverse processes of C1-4Medial scapulaElevation + retraction of scapulaDorsal scapular nerve

NameOriginInsertionActionInnervation

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Muscles Rhomboid MinorRhomboid minorSpinous processes C7-T1Medial border of scapula near spine of scapulaScapular retraction + medial rotationDorsal scapular nerve


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Muscles Rhomboid MajorRhomboid majorSpinous processes T2-5Medial border of scapulaScap retraction + medial rotationDorsal scapular nerve


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Muscles - Pectoralis MajorPectoralis majorSternal + clavicular attachmentsIntertubercular groove (lateral lip)Adduction + IRMedial & lateral pectoral nerves


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Muscles Pectoralis MinorPectoralis minorOuter surfaces ribs 3, 4 & 5Coracoid processMedial rotaion of scapulaMedial pectoral nerve


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Muscles Teres MajorNameOriginInsertionActionInnervationTeres majorDorsal scapula near inferior angleIntertubercular grooveAdduction + IRLower subscapular nerve

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Muscles - LatissimusDorsiLatissimusdorsiThoracolumbar fascia, T6-S5 spinous processes, + iliac crestLower 3-4 ribs, inferior angle of scapula + intertubercular grooveShoulder E from flexed position, sh adduction + IRThoracodorsal nerve


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Muscles Serratus AnteriorSerratus anteriorUpper 8-9 ribsMedial border of scapulaScapular protractionLong thoracic nerve


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Muscles - SubclaviusSubclaviusSubclavian groove on clavicle1st ribStabilise clavicleNerve to subclavius C5,6


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Muscles Biceps BrachiiBiceps brachii long head- short headSupraglenoid tubercle of scapula + glenoidlabrum (lh)Coracoid process (sh)Radial tuberosityShoulder flexion, elbow flexion & forearm supinationMusculocutaneous nerve


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Muscles Triceps BrachiiTriceps brachiilong headlateral headmedial headInfraglenoid tubercle (long)Above spiral groove (lateral)Distal to spiral groove (medial)Olecranon processLong head: sh adductionAll: elbow ERadial nerve


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The rotator cuff muscles (supraspinatus, infraspinatus, teres minor and subscapularis) help to stabilize the humeral head in the glenoidfossa, plus have roles in shoulder rotationRotator Cuff Muscles

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Muscles - SupraspinatusNameOriginInsertionActionInnervationSupraspinatusMedial 2/3 supraspinousfossaGreater tuberosityShabd + dynamic stabilitySuprascapular nerve

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Muscles - InfraspinatusInfraspinatusMedial 2/3 infraspinousfossaGreatertuberositySh ER + dynamic stabilitySuprascapular nerve


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Muscles Teres MinorTeres minorUpper 2/3 lateral border of scapGreater tuberositySh ER +/- adduction, + dynamic stabilityAxillary nerve


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Muscles - SubscapularisSubscapularisMedial 2/3 subscapularfossaLessertuberositySh IR +/- adductionUpper & lower subscapular nerves


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BLOOD SUPPLYV.P

Anterior circumflex humeral vessels

Posterior circumflex humeral vessels

Suprascapular vessels

Subscapular vessels

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NERVE SUPPLY

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Axillary nerve

Suprascapular nerve

Musculocutaneous nerve

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Gateways to the Posterior Scapular RegionSuprascapular Foramen

Quadrangular Space

Triangular Space

Triangular IntervalV.P

Gateways to the Posterior Scapular RegionSuprascapular Foramen

It is formed by suprascapular notch of scapula and the superior transverse scapular ligament,which converts the notch into a foramen.The suprascapular nerve passes trough the suorascapular foramen V.P

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Gateways to the Posterior Scapular RegionQuadrangular Space

Its boundaries are formed by:The inferior margin of the teres minorSurgical neck of humerusThe superior margin of the teres majorLateral margin of the long head of triceps brachii.Axillary nerve and posterior circumflex humeral artery and vein pass trough this spaceV.P

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Gateways to the Posterior Scapular RegionTriangular SpaceIts boundaries are formed byThe medial margin of the long head of triceps brachiiThe superior margin of the teres majorThe inferior margins of the teres minor The circumflex scapular artery and vein pass trough this spaceV.P

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Gateways to the Posterior Scapular RegionTriangular IntervalBoundaries are formed byThe lateral margin of the long head of triceps brachiiThe shaft of the humerus The inferior margin of the teres majorRadial nerve,profunda brachii artery and associated veins pass trough itV.P

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MovementsV.P

The muscles and joints of the shoulder allow it to move through a remarkable range of motion,

Arm flexion(0-135*)Arm extention(45-60*)Arm abduction (0-180*)Arm adduction Medial rotation of the arm (90)Lateral rotation of the arm(0-90*)circumduction (this is a combination of the above movement)V.P

MOVEMENTSMAIN MUSCLEACCESSORY MUSCLEFLEXION0-135*PECTORALISMAJOR(clavicular part)DELTOID ant fibresCoracobrachialisBiceps short headEXTENSION45-60*DELTOID post fibresLATISSMUS DORSITeres majorTriceps long headP major[sternocoastal head]

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ADDUCTIONPECTORALIS MAJORLATISSMUS DORSIBICEPS long headTRICEPS short headTeres majorcoracobrachialisABDUCTIONSUPRASPINATUS[0-15*]DELTOID[15*-90*]SERRATUS ANTERIOR[90*-180*]TRAPEZOIDupper,lower fibres[90-180]

MOVEMENTSMAIN MUSCLEACCESSORY MUSCLE

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MEDIAL ROTATION[INTERNAL]90*PECTORALIS MAJORDELTOID ant fibresLATISSMUS DORSITERES MAJORsubscapularisLATERAL ROTATION[EXTERNAL]70*-90*DELTOID posterior fibresINFRASPINATUSTERES MINOR

MOVEMENTSMAIN MUSCLEACCESSORY MUSCLE

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CIRCUMDUCTIONCombination of different movements, results in hand moving along a circle.

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anatomy of shoulder joint

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