1. CHAPTER 5 Shoulder Complex

2. Review Degrees of freedom - # of planes in which joint moves
Closed packed vs. loose packed position
Closed packed
Maximum area of surface contact; taut capsule; mechanically compressed joint, difficult to distract
Loose/Open-packed
Allowance of motion (spin, roll, slide, etc.)
Resting position: point of least amount of congruency; capsule and ligaments are loosest/slack

3. Diarthrodial (synovial) joints:
Review
Diarthrodial (synovial) joints:
Cartilage
Ligaments
Articular discs
Joint capsule
Synovial fluid
Bursae

4. Introduction
The shoulder is composed of three synovial joints and one pseudojoint.
The shoulder maximizes mobility, but at the sake of stability.
Primary purpose is to position hand for function.

5. Bones Manubrium Clavicle
Superior aspect—contains shallow depression for medial clavicular attachments
Sternal or jugular notch
Clavicle
S-shaped; similar to a crank
Tubular at sternal end; flatter at acromial end

6. Bones Scapula Flat triangular bone
Vertebral border positioned between T2 and T7
Provides location for glenohumeral (GH) muscles to originate and provides stable base from which GH joint can operate

7. Bones
Scapula
Works in concert with clavicle to enhance total shoulder range of motion (ROM)
Has many unique bony prominences:
Superior and inferior angles; spine; borders
Glenoid fossa; acromion; coracoid process
Supraspinatus/infraspinatus/subscapular fossas
Supraglenoid and infraglenoid tubercles

8. Bony Landmark Trails - 1 & 2

9. Bones of the Shoulder and Arm

10. Bones Humerus Bony prominences Greater tuberosity—three facets
Lesser tuberosity
Intertubercular groove
Surgical neck

11. Bones of the Shoulder and Arm
Review tubercles (greater and lesser)
Intertubecular groove

12. Shoulder girdle movements
Joints
Shoulder girdle movements
Elevation/depression
Protraction/retraction
Upward rotation/downward rotation
Scapular tilting—A-P; M-L

13. Joints Sternoclavicular Connects upper extremity to axial skeleton
Saddle joint with three degrees of freedom
Elevation/depression
Protraction/retraction
Rotation

14. Joints Sternoclavicular Ligaments Anterior/posterior Interclavicular
Costoclavicular—clavicle to first rib

15. Trail 3 - S/C Joint
Sternoclavicular Joint

16. Joints Acromioclavicular
Plane synovial joint; three degrees of freedom
Variable presence of articular disc
Likely due to degeneration
Ligaments
Superior/inferior acromioclavicular; coracoclavicular

17. Acromioclavicular—osteokinematics
Joints
Acromioclavicular—osteokinematics
25–30° of upward rotation; A-P axis
Small amounts of tilting
Medial/lateral tilt about a superior-inferior axis
Anterior/posterior tilt about an M-L axis
Recommend inserting Figure 5-13

18. Trail 3 - Acromion, Clavicle
“Springboard Ledge”
Acromion
Clavicle

19. Trail 3 - A/C Joint
Acromioclavicular Joint

20. Joints Scapulothoracic Subscapular bursae/serratus anterior
Functions include:
Maintain length-tension relationship of rotator cuff/deltoid
Position glenoid to receive humeral head
Absorb shock
Permit elevation of body (via scapular depression)
Enhance shoulder ROM

21. Review
Bony landmarks: acromion process, scapular spine, coracoid process, infraspinatous fossa, supraspinatous fossa, inferior angle, medial border, Humerus, deltoid tuberosity, manubrium body, articulating surfaces of sternal and acromial ends
Joints: SC joint, AC joint, GH joint

22. Joints Scapulothoracic Subscapular bursae/serratus anterior
Functions include:
Position glenoid to receive humeral head
Absorb shock
Permit elevation of body (via scapular depression)
Enhance shoulder ROM

29. Joints Scapulothoracic—kinematics 60° of upward rotation
30°from sternoclavicular joint; 30° from acromioclavicular joint
Elevation/depression
10 cm/2 cm
Protraction/retraction
10 cm/5 cm

30. Synergists - Scapula, Adduction and Abduction
(scapulothoracic joint)

31. Joints Glenohumeral joint Ball and socket; three degrees of freedom
Inherently unstable
Humeral head more than twice the size of glenoid
Labrum deepens socket
Large capsule

33. Joints Glenohumeral joint Capsular reinforcements
Superior/middle/inferior GH ligaments
Coracohumeral ligament
Long head of biceps/triceps
Rotator cuff tendons blend with capsule

35. Joints Glenohumeral joint Coracoacromial arch Forms “roof” of GH joint
Subacromial space between humeral head and acromion
Coracoacromial ligament
Subacromial impingement syndrome (SAIS)

36. Joints Glenohumeral joint Bursae Subacromial Subdeltoid
Recommend inserting Figure 5-19

37. Subacromial bursae
Subdeltoid bursae

39. Joints Glenohumeral joint—osteo/arthro kinematics Abduction/adduction
Flexion/extension
Medial/lateral rotation
Lateral rotation
Abduction/adduction—frontal—A-P axis
Flexion/extension—sagittal—M-L axis
Medial/lateral rotation—transverse—superior-inferior axis

40. Joints Glenohumeral joint Bicipital groove
Biceps tendon restrained by coracohumeral and transverse humeral ligament.
During shoulder motion, humerus moves on tendon.
Tendon subject to wear and tear as well as impingement.

41. Scapulohumeral Rhythm
“Setting phase”—highly variable
After 30°, 2:1 ratio evident
120° from GH; 60° from scapula (acromioclavicular + sternoclavicular)
Migrating axis of rotation
Starts from medial root; moves laterally toward acromioclavicular joint
2:1 - for every 2 GH joint, 1 scalpula thoracic joint.
Setting phase:
It preserves the length-tension relationships of the glenohumeral muscles; the muscles do not shorten as much as they would without the scapula's upward rotation, and so can sustain their force production through a larger portion of the range of motion.
It prevents impingement between the humerus and the acromion. Because of the difference in size between the glenoid fossa and the humeral head, subacromial impingement can occur unless relative movement between the humerus and scapula is limited. Simultaneous movement of the humerus and scapula during shoulder elevation limits relative (arthrokinematic) movement between the two bones.

43. Muscles of the Shoulder and Arm - Posterior

44. Muscles of the Shoulder and Arm - Lateral

45. Muscles of the Shoulder and Arm - Anterior

46. Muscles of the Shoulder Complex
Scapular stabilizers
Serratus anterior
Trapezius
Rhomboid major/minor
Pectoralis minor
Levator scapulae

47. Muscles of the Shoulder Complex
Glenohumeral stabilizers
Supraspinatus
Infraspinatus/teres minor
Subscapularis
Biceps/triceps brachii

48. Muscles of the Shoulder Complex
Large movers
Deltoid
Latissimus dorsi
Teres major
Pectoralis major
Coracobrachialis

49. Function of Muscles of the Shoulder Complex
Passive stabilizers
Sternoclavicular and acromioclavicular joints rely on ligaments for support.
GH and scapulothoracic joint rely on muscles for support.
At rest, humeral head suspended by:
Ligaments—superior GH; coracohumeral
Negative Intra-articular pressure
Clavicle and scapula rest on thorax.

50. Function of Muscles of the Shoulder Complex
Dynamic stabilizers
Upper trapezius—low-level activity at rest
Rotator cuff
Biceps

51. Function of Muscles of the Shoulder Complex
Synergistic muscle actions—force couples
Upward scapular rotation
Upper Trapezius—Lower Trapezius—Serratus Anterior
Downward Scapular Rotation
Pectoralis minor—levator scapulae—rhomboids
Shoulder elevation
Deltoid and rotator cuff

52. Function of Muscles of the Shoulder Complex
Muscle forces and moment arm length
Shoulder elevation
30–60° of abduction—supraspinatus > leverage than deltoid
Lever arm length for supraspinatus—remains constant throughout elevation range of motion
Deltoid lever arm length—increases with elevation

53. Finally….! Finished with the shoulder!
Complete trial Guide: pgs 34-38; p.47 (1-10); p.49 1,5,8
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