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OA 4.24

OA 4.24. Identify the three bones that comprise the shoulder joint. Chapter 16 (pp. 388-407). The Shoulder. introduction. Very complicated region Numerous and varied structures Bones, tendons, muscles, nerves, ligaments, bursae, etc. Highly maneuverable

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OA 4.24

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  1. OA 4.24 • Identify the three bones that comprise the shoulder joint.

  2. Chapter 16 (pp. 388-407) The Shoulder

  3. introduction • Very complicated region • Numerous and varied structures • Bones, tendons, muscles, nerves, ligaments, bursae, etc. • Highly maneuverable • 16,000 positions differentiated in 1˚ increments • Combination of four articulations

  4. introduction • Very complicated region • Can be debilitating due to inability to properly use hand(s) • Injuries from: • Direct force/trauma • Secondary forces transmitted proximally • Overuse – predisposition w/overhead movements

  5. introduction • Connection of axial skeleton to upper extremity • Only at SC Joint

  6. stability vs. mobility • The shoulder is inherently unstable • Poor bony stability due to shallow articulation • Stability is gained staticallyby the capsule, ligaments, & labrum; and dynamicallyby the deltoid and rotator cuff muscles.

  7. Stability vs. Mobility CONTINUUM Stabile Mobile As you give up stabilityyou gain mobilityand vice-versa

  8. Skeletal anatomy

  9. humerus (proximal) • Landmarks • Head • Greater tubercle (ant. lat.) • Lesser tubercle (ant. med.) • Bicipital groove(between tubercles)

  10. humerus (proximal) • Landmarks • Anatomical neck (proximal to tubes) • Surgical neck (distal to tubes) • Diaphysis • DeltoidTuberosity

  11. proximal humerus

  12. scapula • Located between Ribs 2-7 • No direct bony or ligamentous attachments • Articulates with clavicle& humerus • Held against torso by muscleattachment & atmosphericpressure • Functions as both apulley and lever

  13. scapula • Glenoid is oriented about 30-45° anterior to the coronal plane of the body • “Plane of the Scapula” • Places Rotator Cuff muscles at optimal length-tension relationship

  14. scapular landmarks • Body – anterior view = (a) • Subscapular fossa • Medial (vertebral) border • Lateral (axillary) border • Superior Border • Glenoid fossa • Acromion process • Coracoid process

  15. scapular landmarks

  16. scapular landmarks • Body • Superior angle • Inferior angle

  17. scapular landmarks • Body – posterior view = (b) • Supraspinous fossa • Infraspinous fossa • Greater Scapular Notch • Spine of scapula • Acromion process

  18. scapular landmarks

  19. scapular landmarks • Body (lateral view) • Glenoid fossa (cavity) • Supraspinous fossa • Acromion process • Coracoid process

  20. scapular landmarks

  21. scapular landmarks • Body – largest portion of scapula • Rotator cuff attachments - fossa • Separated by borders & angles • Spine of scapula • Separates supraspinous/ infraspinousfossae • Extends to form the acromion process

  22. scapular landmarks • Coracoid process – fingerlike projection towards anterior • Glenoid fossa • Articulates with head of humerus – smaller than head • Superior and inferior tubercles • Surrounded by glenoid labrum

  23. clavicle • “Collarbone” • Slender, S-shaped bone articulating w/ sternum & scapula • Helps maintain alignment of scapula • Anchors upper extremity to axial skeleton

  24. clavicle • Medial 2/3 – more cylindrical • Lateral 1/3 – more flat • Structural Weakness? • Change of direction/shape

  25. articular anatomy

  26. articulations • The shoulder is comprised of fourdistinct joints • Sternoclavicular joint • Acromioclavicular joint • Glenohumeral joint • Scapulothoracic joint

  27. sternoclavicular joint (SC) • Articulation of sternum(breastbone) and clavicle at the midline of the body • Anchored by four separate ligaments

  28. acromioclavicular joint (AC) • Articulation of acromion process and clavicle • Three degrees of movement • Elevation/depression • Protraction/retraction • Rotation • Stabilized by three ligaments • Acromioclavicular ligament • Conoid ligament • Trapezoid ligament

  29. AC ligaments

  30. glenohumeral joint (GH) • True shoulder joint • Three degrees of freedom • Flexion/extension • ABD/ADD • IR/ER • Combined movements to form • Horizontal flexion/extension • Circumduction • Elevation

  31. glenohumeral joint (GH) • Supported by numerous ligaments that help to form the joint capsule • Superior GH ligament • Middle GH ligament • Inferior GH ligament • Coracohumeral ligament (coracoid process) • Coracoacromial ligament*

  32. GH joint ligaments Conoid Ligament Trapezoid Ligament

  33. GH articular anatomy • Joint capsule allows for ~1cm of movement • >1cm = laxity • The humerus is oriented at the glenoid at a 30o angle of rotation (____version) • < 30o = anteversion • > 30o = retroversion

  34. Scapulothoracic joint (ST) • Not a true joint – no bony articulations • Three degrees of movement • Elevation/depression • Protraction/retraction • Upward/downward rotation • Most important joint for shoulder mechanics • Starting point in the chain of motion • Produces movement at AC & SC joints

  35. scapulohumeral rhythm • The scapula and humerus move at differing degrees during ABD • Humerus moves first 30o • Scapula & humerus move at 1:2 ratio for next 60o • Scapula & humerus move at 1:1 ratio past 90o ABD

  36. muscular anatomy

  37. ST vs. GH muscles • Scapulothoracic muscles move the scapulaon the axialskeleton • Direct vs. indirect based on attachments • Glenohumeral muscles move the humeruson the scapula

  38. Scapulothoracic muscles • Trapezius • Superior • Middle • Inferior • Levator scapulae • Rhomboids • Major • Minor • Latissimus dorsi

  39. Scapulothoracic muscles • Serratus anterior • Pectoralis major • Pectoralis minor

  40. glenohumeral muscles • Deltoid • Anterior • Middle • Posterior • Triceps brachii • Biceps brachii • Teres major • Coracobrachialis

  41. OA 4.29 • Identify the 4 muscles of the rotator cuff and their corresponding fossae • Identify 3 functions of the rotator cuff

  42. glenohumeral muscles • Rotator cuff muscles • Supraspinatus • Infraspinatus • Teres minor • Subscapularis

  43. rotator cuff muscles • Functions • Holds head of humerus in glenoid fossa • Rotation of humerus on long axis (IR/ER) • Protects shoulder joint via common musculotendinous sheath • Stabilizes shoulder joint in every direction EXCEPTinferiorly

  44. rotator cuff muscles • Rotator Cuff Problems • Rupture of rotator cuff muscles • Calcification of tendons • Humeral subluxation or dislocation • Superiorly: stabilized by supraspinatus & coracoacromial arch • Posteriorly: stabilized by infraspinatus & teres minor • Anteriorly: stabilized by subscapularis • Inferiorly: NO muscular support

  45. rotator cuff muscles

  46. muscular anatomy

  47. other anatomy

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