Shoulder Anatomy

1. Shoulder Anatomy Morgan A. Scott

2. Anatomy of the Shoulder • Bones that make up the shoulder complex and shoulder joint: • Clavicle • Scapula • Humerus

3. Anatomy continued… • Clavicle • Slender S-shaped bone approximately 6 inches long. • Provides support to anterior portion of shoulder. • Extends from the sternum to the tip of the shoulder (Acromion process). • Very superficial--- subject to direct blows.

5. Scapula • Flat, triangular-shaped bones • Serves mainly as an articulating surface for the head of the humerus. • Located on dorsal aspect of thorax. • Has three prominent projections: • Spine • Acromion • Coracoid process

7. Humerus • Head of the humerus is spherical, with a shallow, constricted neck; it faces upward, inward, and backward, articulating with the glenoid fossa. • Around the humeral head is the anatomical neck, which serves as an attachment for articular capsule. • Greater and lesser tubercle are located adjacent and immediately inferior to the head. • Bicipital groove.

9. Articulations • 4 major articulations associated with shoulder complex: • Sternoclavicular • Acromioclavicular • Glenohumeral • Scapulothoracic

10. Sternoclavicular Joint • Clavical articulates with the manubrium of the sternum. • This is the only direct connection between the upper extremity and the trunk. • Acromioclavicular joint • Gliding articulation of the lateral end of the clavicle with the acromion process.

11. Glenohumeral Joint • Ball and Socket joint • The round head of the humerus articulates with the shallow glenoid cavity of the scapula. • Scapulothoracic • Not a true joint; however, the movement of the scapula on the wall of the thoracic cage is critical to the shoulder joint.

12. Shoulder Ligaments • Sternoclavicular Joint Ligaments • The SC joint is a weak joint because of its bony arrangement, but it is held securely by strong ligaments that pull the sternal end of the clavicle downward and toward the sternum. • Main Ligaments • Anterior sternoclavicular • Posterior sternoclavicular • Interclavicular • Costoclavicular

13. Acromioclavicular Joint Ligaments • Anterior • Posterior • Superior • Inferior • In addition to the AC joint Ligament, the coracoclavicular ligaments joins the coracoid process and the clavicle and helps maintain the position of the clavicle relative to the acromion. • The coracoacromial ligament connects the coracoid to the acromion.

14. Glenohumeral Ligaments • Surrounding the GH joint is a loose, articular capsule. • It is strongly reinforced by the superior, middle, and inferior glenohumeral ligaments and by the tough coracohumeral ligament- which attached to the coracoid process. • The transverse ligament retains the long biceps tendon within the bicipital groove by passing over it from the lesser and greater tuberosities.

15. Muscles • Produce dynamic motion & establish stability to compensate for the greater mobility • Motions at shoulder joint • flexion & extension • Internal & external rotation • Abduction & Adduction • Horizontal flexion • Circumduction

16. Muscles • Muscles originating on the axial skeleton and attaching to the humerus • Latissimusdorsi • Shoulder extension, adduction • Pectoralis major • Shoulder adduction, horizontal flexion

17. Muscles • Muscles attaching scapula to humerus • Deltoid • Abduction, flexion, extension • Teres major • Internal rotation • Coracobrachialis • Shoulder flexion • Rotator cuff muscles • Supraspinatus-external rotation, initiates abduction • Infraspinatus-external rotation • Teres minor-external rotation • Subscapularis-internal rotation

18. Muscles • Muscles attaching axial skeleton to scapula • Levator scapula • Shoulder elevation • Trapezius • Shoulder elevation, retraction, depression • Rhomboids (major & minor) • Shoulder retraction • Serratus anterior • Shoulder protraction, holds scapula flat against thoracic cage

19. Muscles • Other Muscles • Biceps brachii—long head & short head • Shoulder flexion • Triceps brachii—long head, medial head, lateral head • Shoulder extension

20. Preventing shoulder injuries • Maintain adequate strength & flexibility of all shoulder muscles • Good posture • Proper techniques • Proper warmup • Proper protective gear

21. Types of Injuries • Sprains • Dislocations • Strains • Overuse • Fractures

22. AC Sprain Shoulder separation

23. Mechanism • Impact to tip of shoulder • Fall on outstretched arm

24. Signs and symptoms • Deformity at AC joint • distal end of clavicle rides superiorly • Pain with movement and palpation • “+” piano key sign

25. Degrees of injury • 1st degree: no deformity, pain w/ palpation & motion, mild stretching of AC ligament • 2nd degree: displacement of distal end of clavicle, unable to abduct arm or bring it across body, pain • 3rd degree: complete rupture of AC and CC ligaments, with dislocation of the distal end of clavicle, severe pain, LOM, instability

26. Treatment • RICE • Immobilization • Physician referral if more than 1st degree • Possible surgery

27. SC Sprain • Relatively uncommon injury

28. Mechanism of injury • Indirect force transmitted through the humerus, the shoulder joint and the clavicle • Direct impact to clavicle

29. Signs & symptoms • 3 degrees • May have deformity at sternal end • Swelling • Pain • POT • Inability to abduct shoulder through full ROM

30. Treatment • RICE • Immobilization • Physician referral

31. Glenohumeral dislocation • Shoulder dislocation • Anterior—most common • Posterior • Inferior • Multidirectional

32. Anterior shoulder dislocation

33. Anterior shoulder dislocation

34. Mechanism • Arm forced into external rotation abduction and extension • Posterior force driving the head of the humerusAnteriorly

35. Signs & symptoms • Deformity—step off (deltoid will look flattened • Arm in slight abduction, external rotation • Will not be able to move shoulder joint • Unable to touch opposite shoulder with hand of affected side • Pain and POT

36. Treatment • Immobilization • ER to have shoulder reduced by a physician • Immobilization for 1-2 weeks • No activity 4-6 weeks • Rehab-ROM and strengthening • High incidence of recurrence after the first dislocation

37. Shoulder reduction

38. Shoulder dislocation video • Watch shoulder dislocation on Google Video.htm

39. Shoulder subluxation • Partial dislocation/spontaneous reduction

40. Mechanism • External rotation, abduction, extension

41. Signs & symptoms • Pain • Limited ROM • POT

42. Treatment • Ice • Immobilization • Physician referral • Rehab—strengthening muscles around joint

43. Rotator Cuff Strain • 3 degrees • Most involve supraspinatus • Tears usually at insertion on humerus

44. Rotator cuff strain

45. Mechanism • Dynamic rotation of arm at high velocity (overhead throwing) • Usually involves individuals with a history of impingement or instability

46. Signs & symptoms • Pain w/ muscle contraction • POT over greater tuberosity • Loss of strength • Complete tear produces pain, loss of function, swelling and POT

47. Treatment • RICE • Decrease level of activity • Exercises to strengthen rotator cuff

48. Biceps tendon rupture

49. Mechanism • Direct blow • Severe contraction of biceps

50. Signs & symptoms • Unable to flex elbow • Deformity of biceps—balling up of muscle belly • Pain • POT