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Biomechanics of shoulder
- 2. 5-2 #Shoulder joint is a complex joint composed of clavicle,scapula & humerus. #It links the upper extremity to the thorax or axial skeleton.
- 3. SHOULDER COMPLEX consists of 3 joints: -STERNOCLAVICULAR JOINT -ACROMIOCLAVICULAR JOINT -GLENOHUMERAL JOINT
- 5. Joint between medial end of clavicle and superolateral aspect of manubrium. Links the upper extremity directly to thorax. True synovial joint.,has a fibrocartilagenous articular disc which divides it into 2 compartments. Stabilizers of SC Joint: -Costoclavicular ligament -Interclavicular ligament -Sternoclavicular ligaments Articular disc,anterior,posterior,costoclavicular and interclavicular ligaments maintans joint apposition. Sternoclavicular ligaments-prevents anterior and posterior translations.
- 6. Costoclavicular ligament-limits upward and posterior displacement of clavicle. Interclavicular ligaments-restraint SC Joint superiorly.Posterior portion restraints anterior translation of SC Joint. Articular Disc-prevents medial displacement of clavicle while carrying objects at the side as well as inferior displacement of clavicle via articular disc.
- 8. Joint between lateral end of clavicle & acromion of scapula. Synovial joint Articular Disc present. ACROMIO-CLAVICULAR LIGAMENT: -Superior AC Ligament -Inferior AC Ligament :Appose articular surfaces. :Restraints axial rotation & posterior translation of clavicle. CORACOCLAVICULAR LIGAMENT: -Conoid part: triangular shape vertically oriented. posteromedially directed limits sup inf displacement of clavicle -Trapezoid part:quadrilateral shape horizontal in orientation
- 9. -lat & ant to conoid lig. -anterolaterally directed -provide resistance to post. translatory forces applied to distal clavicle.
- 12. Joint between glenoid fossa of scapula and head of humerus. Ball and socket joint. Glenoid fossa faces slight anteriorly. Angle of Inclination:angle b/w long axis through the shaft of humerus and the axis passing though the centre of the humeral head.Normal value is 130-150 deg. In frontal plane. Angle of torsion:the angle b/w the axis through the humeral haed and neck & an axis
- 13. the humeral condyles in the transverse plane.Normal value is 30deg. posteriorly.Thus the humeral head pos. is normally posterior torsion or RETROVERSION of the humerus. GLENOID LABRUM- -Inc. total available articular surface by increasing depth or curvature of glenoid fossa. GLENOHUMERAL CAPSULE- -Large & loose capsule surrounding GH joint. -Taut superiorly & slack anteriorly and inferiorly when the arm at the side of the body.
- 14. GLENOHUMERAL LIGAMENTS- -Reinforce GH capsule (extensions of ant. Joint capsules. 1) Superior GH lig. 2) Middle GH lig.-secondary restraint to inf. Translation of GH joint with arm abducted & externaly rotated position.also act as restraint to ant. Translation with arm abducted to 45deg. 3) Inferior GH lig-3 components(ant. Band,post. Band & axillary pouches -primary ant. Stabilizer with arm 90 deg. Abduction.
- 16. CORACO-HUMERAL LIGAMENT: -Resraints inf.translation of humeral head in dependent arm. CORACO-ACROMIAL ARCH: -Osteo-ligamentous vault-covers humeral head,forms a space with in which lie the subacromian bursa,rotator cuff &a portion of long head of biceps. -consist of coracoid process posteriorly ,acromian process anteriorly and coracoacromial lig. Superiorly. -Functions:1)protection of humeral head
- 17. against the impingement 2)prevents humeral head from dislocating superiorly. BURSAE: Subacromial or Subdeltoid Bursae. Permits frictionless movement b/w humerus & supraspinatus tendon.
- 19. STERNO-CLAVICULAR JOINT: 3 Rotatory degrees of freedom of SC Joint : 1)Elevation & Depression of clavicle: Around AP axis. :ROM-Elevation:48 deg. -Passive depression:15 deg. :Lateral clavicle rotates upward in Elevation & downward in Depression. 2)Protraction & Retraction of clavicle:Around vertical(supero-inferior) axis. :ROM-Protraction:15-20 deg. -Retraction:20-30 deg. :Lateral clavicle rotates anteriorly in Protraction & posteriorly in Retraction.
- 20. 3)Anterior& Posterior Rotation of Clavicle: :Occurs around a longitudanal axis through clavicle intersecting SC & AC joints. :Clavicle rotates posteriorly from its neutral position and then , rolls anteriorly from its fully rotated position. :ROM:Posterior Rotation:50 deg. :Anterior Rotation:10 deg.
- 23. ACROMIO-CLAVICULAR JOINT: 1)INTERNAL/EXTERNAL ROTATION: :Occurs around vertical axis through AC Joint. :Brings glenoid fossa anteromedially (Int.rotation) & posterolaterally(Ext.rotation). :Maintain contact of scapula with horizontal curvature of thorax when clavicle protracts &retracts as a result of humeral elevation. :Normal value:30 deg. 2)ANTERIOR/POSTERIOR TIPPING :Tilting of scapula in relation to clavicle.
- 24. :Occurs around an oblique “coronal axis” through AC Joint. :Anterior Tipping:Acromion process tips forward & inf. Angle tips backward. :Posterior Tipping:Acromion Process tips backward & inf. Angle tips forward. :Normal value:60 deg. 3)UPWARD/DOWNWARD ROTATION :Rotation of glenoid fossa upward or downward. :Upward rotation: Coracoid process move inferiorly but restricted due to tension in coraco-clavicular ligament. :Normal value:30 deg.
- 27. GLENO-HUMERAL JOINT: *FLEXION/EXTENSION: -Occurs around coronal axis passing through axis of humeral head. -Flexion:0-120 deg. -Extension:0-50 deg. *ABDUCTION/ADDUCTION: -Occurs around an AP Axis passing through humeral head. -Abduction:0-120 deg.(with the movement of scapula) -Adduction:120-0 deg.
- 28. *MEDIAL/LATERAL ROTATION: -Occurs around a long axis parallel to shaft of humerus & passing through the centre of humeral head. -Normal value:0-90 deg. *SCAPTION/SCAPULAR ABDUCTION: -Abduction/elevation of humerus in the plane of scapula.
- 29. 5-29
- 32. *FLEXION:Clavicular fibres of Pectoralis major :Anterior fibres of Deltoid :Coracobrachialis :Short head of Biceps *EXTENSION:Posterior fibres of Deltoid :Lattisimus Dorsi :Teres Major :Sternocostal head of Pectoral major *ADDUCTION:Pectoralis major :Lattisimus dorsi :Long head of Triceps :Teres major :Coracobrachialis
- 33. *ABDUCTION:Deltoid(Middle fibres) :Supraspinatus :Serratus Anterior :Upper & lower fibres of Trapezius. *MEDIAL ROTATION:Pectoralis major :Anterior fibres of Deltoid :Lattisimus Dorsi :Teres major :Subscapularis *LATERAL ROTATION:Posterior fibres of Deltoid :Infraspinatus :Teres minor :
- 35. Kinetics include the forces which produces the motions & stability of GH Joint during rest and motions. STATIC STABILIZATION OF GH JOINT -Includes stabilization of humeral head when the arm is at the side unloaded & loaded. -Arm unloaded at the side:Resultant pull of LOG and Rotator Interval capsule creates a line of force which compresses humeral head against lower portion of glenoid fossa.
- 36. -Airtight seal of capsule-creates –ve intraarticular pressure which prevents inf. translation of humerus by force of gravity. -Degree of glenoid inclination-upward tilt of scapula produces a partial bony block against humeral translation. -If the arm is heavily loaded-Supraspinatus recruited which has attachments to rotator interval capsule.
- 37. T H A N K YOU