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Shoulder Biomechnics - Dr.BHARTI PAWAR (PT).pptx

The document discusses the anatomy and biomechanics of the shoulder complex. It describes the bones, joints, ligaments, muscles, and movements involved. Key points include: - The shoulder complex includes the clavicle, scapula, and humerus joined by the sternoclavicular, acromioclavicular, and glenohumeral joints. - The scapulothoracic joint allows movements of the scapula on the thorax. The sternoclavicular joint permits elevation, depression, protraction, and rotation of the clavicle. - The glenohumeral joint is a ball and socket joint that allows flexion, extension,

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SHOULDER COMPLEX – BIOMECHNICS Dr.BHARTI PAWAR (PT)
Anatomy Shoulder Complex is Composed of Clavicle Scapula Humerus & Joints that link this bones together
JOINTS IN SHOULDER COMPLEX Anatomic ⚫ Sterno Clavicular (SC) ⚫ Acromioclavicular(AC) ⚫ Glenohumeral (GH) Functional ⚫ Scapulothoracic
SCAPULO THORACIC JOINT ⚫ Articulation of scapula with thorax, depends on anatomic SC & AC joints ⚫ Position of Scapula on post thorax  2 inches from midline & from 2nd to 7th rib,  Lies 30o - 40o forward plane & is tipped anteriorly 10o - 20o
MOVEMENTS IN SCAPULOTHORACIC JOINT 1. Elevation Depression 2. Protraction Retraction (Abduction/Adduction) 3. Upward & downward rotation 4. Anterior & Posterior Tipping
ANGLEOFINCLINATION&ANGLEOFTORTION ⚫ Angle of Inclination -Angle formed by Intersection of axis through humeral head & Longitudinal Axis of shaft of Humerus - 130o – 150o ⚫ Angle of Torsion – Formed between Axis through axis through humeral condyles & Axis through Humeral head – 30o posterior
STERNOCLAVICULARARTICULATION ⚫ IS Between two saddle shape surfaces, Synovial saddle jt, 30 Freedom 1) Sternal end of clavicle 2) Notch formed by manubrium of sternum & 1st costal cartilage • Ends are invaribly congruent ( little contact between articular surfaces & Concave convex at both articulating surfaces)
STERNOCLAVICULAR DISK ⚫ Superior portion of middle clavicle does not contact manubrium instead serves as attachment to joint disk & interclavicular lig ⚫ Fibro cartilage joint disk is attached superiorly to clavicle & lower portion to the manubrium & 1st costal Cartilage
FUNCTIONS OF STERNO CLAVICULAR DISK Acts as pivot during SC motions Upper end serves as pivot during Elevation-Depression & lower end during protraction- retraction  Stability by increasing joint congruency, Shock Absorption Absorbs medially directed forces from lat end of clavicle Unique diagonal attachment prevents clavicle to override shallow manubrium facet
STERNOCLAVICULAR JOINT MOTIONS KINEMATICS  3o freedom 1. Elevation ( 45o ) Depression (15o ) 2. Protraction (15o ) Retraction (15o ) 3. Anterior (0o - 5o ) Posterior rotation (25o - 55o )  During Elevation & Depression disk remains stable  During protraction & retraction disk moves along with clavicle
A. Elevation & Depression ⚫ A- P / Saggital Axis & Frontal Plane ⚫ During elevation middle clavicle surface slides downwards on mnubrium & during depression it slide upwards ⚫ Evelation & Depression of Clavicle is associated with elevation & depression of scapula
B. Protraction & Retraction ⚫ Vertical Axis & Transverse Plane ⚫ During Protraction & Retraction articular disk moves along with the clavicle ⚫ Medial surface of clavicle moves in same direction of lat end of clavicle
C. Ant-Post/Upward-downward rotation of clavicle ⚫ Longitudinal Axis , Saggital plane ⚫ Rotation occurs as spin between saddle shaped surface of clavicle & manubriocostal facet with scapular rotation movts ⚫ During post(upward) rotation inferior surface of clavicle faces anteriorly ⚫ upward rotation of scapula will lead to posterior rotation of clavicle
LIGAMENTS – KINETICS ⚫ Capsule all around ⚫ Inter clavicular lig checks excessive depression ⚫ Anterior & Posterior sternoclavicular lig (checks Protraction & Retraction) ⚫ Costocalvicular lig Provides inferior stability & counter balance superiorly directed forces
ACROMIO-CLAVICULAR JOINT Plane Synovial 3o of Freedom ⚫ Articulation between Lateral end of clavicle with acromion process (Reciprocally Concave Convex or reverse)
ACROMIO-CLAVICULAR JOINT conti… ⚫ Inclination of articulating surfaces varies individual to individual hence arthrokinematis is unpredictable ⚫ Function – Maintain relation between clavicle and scapula during movements of shoulder joint
MOVEMENTS IN AC JOINT occurs with movements of Scapula ⚫ Anterior & Posterior Tipping ⚫ Upward & downward rotation ⚫ Elevation of upper arm (Jointly occurs with ant tipping & Posterior rotation of Clavicle)
Ligaments ⚫ AC disk Variable in size & differs among individuals, various times in life, between sides of same individual ⚫ Separates articulating surfaces & Acts as pivot point
Ligaments ⚫ AC Ligament is composed of parallel fibers gives horizontal stability ⚫ CC Ligament firmly unites clavicle & scapula, Rotatory stability 1. Trapezoid part (Lat & Quadrilateral in shape) 2. Conoid Part(Med & Post to trapeziod, Tringular in shape)
SCAPULOHUMERALRHYTHM ⚫ Coordinated motion of scapula and humerus experienced during shoulder movement ⚫ Ratio of 2:1 (2 degrees of humeral flexion/abduction to 1 degree of scapular upward rotation)
GLENOHUMERAL JOINT Synovial Joint Ball & Socket Variety , 3o of Freedom  Articulating Surface o Glenoid fossa o Head of Humerus
SUPPORTING STRUCTURES OF GH JOINT ⚫ Glenoid Labrum ⚫ Joint Capsule ⚫ Glenohumeral Ligament (Sup, Middle, Inferior GH Lig) ⚫ Coraco acromial Ligament ⚫ Surrounding Musculature
GLENOID LABRUM ⚫ Fold of Dense fibrous connective tissue with little fibro cartilage ⚫ Attached periphery of glenoid fossa enhancing depth & curvature of fossa
GLENOID LABRUM CONTI…….. ⚫ Superiorly it is loosely attached & inferior portion is firmly attached & relatively less mobile ⚫ When Arm is resting independently at side two articulating surfaces has very little contact & posterior head rest only on small inferior portion of fossa
GLENOHUMERAL JOINT CAPSULE ⚫ Capsule is twice the size of humeral head ⚫ In loose pack position it allows 1 inch of dislocation of head from glenoid fossa ⚫ In resting position capsule is taught superiorly & lax inferiorly
GLENOHUMERAL JOINT CAPSULE Conti… ⚫ Capsule is supported o superiorly by –Coracohumeral lig o Anteriorly by – 3 GH lig o Posteriorly by rotator cuff
GLENOHUMERAL LIGAMENTS ⚫Superior GH Lig ⚫Middle GH Lig ⚫Inferior GH Lig ⚫Coracohumeral Lig ⚫Coracoacromial Lig ⚫Transverse Humeral Lig
BURASAE IN SHOULDER JOINT ⚫ Subacromial Bursa (Permits Smooth gliding of Supraspinatus & head of Humerus) ⚫ Subdeltiod Bursa ( Smooth gliding of Deltoid & Acromion Process)
BURASAE IN SHOULDER JOINT  Subcoracoid Bursa ⚫ Functions –  Reduce friction between coracobrachialis, subscapularis & short head of biceps tendons, thus facilitating internal & external rotation of shoulder. Subsscapular Bursa Reduces Friction of superficial fibers against scapular neck, humeral head & coracoid process.
CORACOACROMIALARCH When suprahumeral space is narrowed impingement of supraspinatus tendon &subacromian bursa increases& causes painful supraspinatus impingement syndrome Formed by coracoid process,Acromion & Croraco-acromial lig (Osteoligaments vault) ⚫ Structures bet arch are subacromiom bursa& supraspinatus tendon , Portion of Long head of biceps ⚫ Functions- ⚫ Prevents superior disloccation of head of humerus
MUSCLES Flexors ⚫ Deltoid ⚫ Pectoralis Major ⚫ Short head of Biceps ⚫ Coracobrachailis Extensors ⚫ Teres Major ⚫ Long head of Triceps ⚫ Latisimus Dorsi
MUSCLES Abductors Adductors ⚫ Teres Major ⚫ Pectoralis Major ⚫ Short head of Biceps ⚫ Long Head of Triceps ⚫ Coracobrachlis ⚫ Supraspinatus ⚫ Deltoid ⚫ Serratus Anterior ⚫ Upper & Lower fibers of Trapezious
MUSCLES Medial Rotators ⚫ Deltoid ant Fibers ⚫ Pectoralis Major ⚫ Latisimus Dorsi ⚫ Teres Major Extensors ⚫ Deltoid Post Fibers ⚫ Infraspinatus
KINEMATIS OF GLENOHUMERALJT  Osteokinamatics  Flexion Extention • Frontal Axis, Saggital Plane • Flex-120o (GH) + 60o(ST) = 180o • Exten-50o – 60o
KINEMATIS OF GLENOHUMERALJT CONTI….  Osteokinamatics  Abduction Adduction • Saggital Axis, Frontal Plane • Abduc-120o (GH) + 60o(ST) = 180o • Adduc- 120o - 0o • Medial Lateral Rotation • Vertical Axis, Horizontal Plane • MR-70o, LR- 90o
⚫ Arthrokinematics ⚫ Concave Convex Rule – (Glenoid fossa is Concave & Humeral Head is Convex) ⚫ Convex head is substantially larger surface & has different radius of curvature then shallow concave fossa KINEMATIS Conti…
⚫ Arthrokinematics Conti….. ⚫ During Abduction Movement- Superior rolling & Translation & Inferior gliding occurs ⚫ Humeral head is translated 1- 2mm superiorly during elevation of arm KINEMATIS Conti…
Arthrokinematics Conti… ⚫ Abduction ( 120o+ 60o =180o) ⚫ Restriction to abduction is caused by impingement of greater tubercle on coracoacromial arch ( at 90o abduct) Hench humerus is laterally rotated 35o - 40o so greater tubercle will pass under or behind arch & further abduction can be continued without impingement
KINETICS LIGAMENTS ⚫ Superior GH Lig originates from anterior superior labrum & inserted on lesser tuberosity ⚫ Function- Primary restrain to inferior translation of adducted shoulder at neutral position , MGH Lig & IGH lig are lax in this position
Ligaments conti.. ⚫ Middle GH Lig originates from anterior superior labrum, Supra glenoid tubercle & inserted on lesser tuberosity ⚫ Function- o Primary restrain to inferior translation when arm is abducted & ex rotated. o Restrain anterior translation having its maximumal exffect when arm abducted 45o
ligaments conti.. ⚫ Inferior GH Lig originates from inferior labrum & inserted on anatomic neck of humerus 1) Anterior Band 2) Posterior Band 3) Axillary band
ligaments conti.. ⚫ Functions- o Primary restrain to anterior& inferior translation when arm is abducted 90o o Ant band restrains anterior translation when arm is abducted & externally rotated o Post band restrains posterior translation when arm is abducted and internally rotated
 Coracohumeral Lig ⚫ Originates from coracoid process & has two bands – One insreted on lesser tubercle –Second inserted on greter tubercle ⚫ Long head of biceps passes through tunnel between this two bands ⚫ Functions: ⚫ Inferior translation of Humeral head
kinetics conti… ⚫ Stability of shoulder joint is provided by static & Dynamic structures ⚫ Static stabilizers are passive structures & dynamic are musculature surrounding shoulder joint
STATIC STABILITY ⚫ In resting position humeral head is not in contact with glenoid fossa or it rest on inferior glenoid fossa ⚫ Gravity acts on humerus parrellal to shaft in downward direction ⚫ This could require a verticle upward pull to restore equilibrium
Static Stability Conti…. ⚫ Such vertical force could only be supplied by muscles such as deltoid, long head of biceps & triceps. ⚫ Muscles are electrically silent in relax unloaded position hence gravity is offset by a force that can apply a torque of equal magnitude in opposite direction and this force is genarated by static stabilizers
STATIC STABILIZERS ⚫ Articular Incongruence - Glenoid Fossa, Angle of inclination & Torsion ⚫ Glenoid Labrum by incresing depth by 50%, Suction effect & Adsive cohessive forces ⚫ Joint Capsule by Intracapsular Pressure ⚫ Ligaments ( SGH,MGH,IGH) ⚫ Joint Cohesion ⚫ Intra-articular negative Pressure
DYNAMIC STABILIZERS  DELTOID FORCE COUPLE  In neutral position deltoid has small angle of application/Moment arm for abduction as compare to supraspinatus & line of pull is directed superiorly  Hence force generated by middle deltoid tends to produce superior translation of head on glenoid fosssa rather than abduction rotation
SUPRASPINATUS FORCE COUPLE ⚫ In neutral position abduction moment of supraspinatus is slightly greater than deltoid ⚫ Hence in initial abduction Supraspinatus has mechanical advantage and its contraction trends to produce abduction while simultaneously compressing GH joint Dig shows line of action of Supraspinatus
Conti ….. ⚫ However physiological cross section areas of supraspinatus is smaller than that of deltoid and consequently supraspinatus is incapable of generating large abduction moments ⚫ Hence further Powerful abduction requires simultaneous activity of both deltoid & supraspinatus
DELTOID & INFRSPINATUS, TERES MINOR & SUBSCAPULARIS FORCE COUPLE ⚫ Unrestricted superior glide of humeral head results in compression of contents of subacromial space ⚫ Hence when deltoid contracts all rotator muscles are also initiated and contracts to exert compressive force on proximal humerus holding head of humerus firmely against glenoid fossa ⚫ Simultaneously teres minor lower portion of infraspinatus & subscpularis apply inferior force on humeral head giving additional stability/protection against superior glide of humerus Dig shows line of action of SIT
Conti… ⚫ Contraction of SIT with deltoid forms an anatomical force couple in which upward and downward full of muscles are balances and forces contribute to abduction ⚫ Thus abduction & Elevation of arm depends on 3 factors 1) Deltoid full 2) Supraspinatus full 3) SIT full
SUMMARY OF DYNAMIC STABILIZATION  Deltoid provides strength to the movement  Supraspinatus provides mechanical advantage early in ROM  Rest of Rotattor cuff provides joint compression throughout ROM  SIT provides stability to humeral head in inferior direction  Lost of any of this results in significant impairment in ability to elevate shoulder
Shoulder Biomechnics - Dr.BHARTI PAWAR (PT).pptx