2. Elevation/Depression

3. Protraction/Retraction

4. Internal/external rotation

5. Anterior/posterior tiping

6. Static stabilization of the GH
Due to incongruence of the GH articular surfaces, the bony surfaces alone cannot maintain joint contact in dependent position (arm hanging at the side).
LOG pull the humeral head inferiorly it need an equal upward pull to stabilize, such an upward pull is could be supplied by muscles such as deltoid, supraspinatus, and long head of biceps but the EMG shows these muscle are electrically silent, thus the stabilization in this dependent position is passive, the superior capsule, SGHL, CH ligament, are taut during relaxed dependent position. The resultant pull of LOG and these structure create a force which compresses the head in Glenoid fossa
Healthy GH joint is seal by labrum and capsule, any translation produces a negative pressure that resist the inferior translation. Any tear in labrum thus results in

7. Static stabilization of the GH
Degree of Glenoid inclination also play a role in static stability , if there is upward inclination either structurally or by upward scapular rotation will resist more inferior translation of the humeral head.
If the arm is loaded then the passive restraints are inadequate to resist the translation then the supraspinatus is recruited because the supraspinatus is attached on the capsular structures, paralysis of the supraspinatus causes inferior subluxation of the humeral head due to sustained forces which causes the capsule to b e lax.

9. Dynamic stabilization of GH The deltoid and GH stabilization
Generally deltoid is considered as prime mover for flexion and abduction however the resultant action of the deltoid muscle is used in stabilization of the GH joint during elevation

10. The RC and GH stabilization
The supraspinatus, infraspinatus, teres minor, and subscapularis muscles compose the rotator or musculotendinous cuff (also referred to by the acronym SITS muscles)
These muscles are the GH joint compressor during elevation, these muscles and deltoid muscle make force couple

12. The supraspinatus and GH stabilization
Unlike other RC muscles the suprspinatus has a superior translatory component rather than inferior component that’s why can,t offset the superior translation of the deltiod. However the supraspinatus muscles rotatory component is larger than that of other RC muscles
The supraspinatus has a large moment arm that is capable of independently producing abduction full range of GH joint simultaneously stabilizing it
Gravity also paly in stabilizing by offsetting the upward pull of the supraspinatus and deltoid muscles

14. The long head of bicep and GH stabilization
The long head of the biceps brachii runs superiorly from the anterior shaft of the humerus through the bicipital groove between the greater and lesser tubercles to attach to the supraglenoid tubercle and superior labrum. It enters the GH joint capsule through an opening between the supraspinatus and subscapularis muscles, where it penetrates the capsule but not the synovium
The long head of the biceps brachii, because of its position at the superior capsule and its connections to structures of the rotator interval capsule to be part of the reinforcing cuff of the GH jointThe biceps muscle is capable of contributing to the force of flexion and can, if the humerus is laterally rotated, contribute to the force of abduction and anterior stabilization.

16. Pairing of Pec Girdle and Shoulder Joint Movements
Shoulder Jt
Shoulder Girdle
Abduction
Upward rotation
Adduction
Downward rotation
Flexion
Elevation / upward rotation
Extension
Depression / downward rotation
Internal rotation
Abduction (protraction)
External rotation
Adduction (retraction)
Horizontal abduction
Horizontal adduction

17. Orientation Muscles of the Pectoral Girdle
Muscles of the thorax that move the pectoral girdle
Anterior thoracic muscles
Posterior thoracic muscles
Muscles of the thorax that move the humerus.
Axial muscles that move the humerus
Scapular muscles that move the humerus.

18. Muscles of the Thorax Move the Pectoral Girdle
Anterior thoracic muscles
Subclavius
Pectoralis minor
Serratus anterior
Posterior thoracic muscles
Fiber of trapezius
Levator scapulae
Rhomboid minor
Rhomboid major

19. Muscles of the Thorax that Move the Humerus
Axial muscles
Pectoralis major
Latissumus dorsi
Scapular muscles
Fiber of deltoid
Rotator cuff
Teres major
Coracobrachalis
Long & short head of biceps
Long head of triceps

20. ORIGIN, INSERTION, ACTIONS AND NERVE SUPPLY

21. Subclavius Muscle Subclavius Origin – 1st rib
Insertion – lower surface of clavicle
Action
Depression and move clavicle anteriorly
Helps stabilize pectoral girdle
Nerve supply
Subclavian nerve
Subclavius

22. Pectoralis Minor Origin
2nd - 5th ribs, 3rd – 5th ribs or 2nd – 4th ribs.
Insertion
Coracoid process of scapula
Action
Abduction scapula and rotates it downward
Elevate the ribs during forced inhalation.
Nerve supply
Medial pectoral nerve

23. Pectoralis Minor

24. Serratus Anterior Origin – Superior 8 or 9 ribs
Insertion – vertebral border and inferior angle of scapula
Action
Abduction and rotates the scapula upward
Elevate ribs when scapula stabilized.
Also known as “boxer’s muscles”
Nerve supply
Long thoracic nerve

25. Fiber of Trapezius Consists 3 fibers
Superior or upper fiber, middle fiber and inferior or lower fiber.
Important for move the scapula.
Nerve supply - accessory nerve and cervical spinal nerve.

26. Upper / Superior Fiber of Trapezius
Origin – medial one third of the superior nuchal line, external occipital protuberance and ligamentum nuchae.
Insertion – posterior border of the lateral one third of the clavicle.
Action – scapular elevation

27. Middle Fiber of Trapezius
Origin – spinous process of T1 – T5
Insertion – medial border of the acromion process of scapula, and superior border of the spine of the scapula.
Action – scapular adduction.

28. Lower / Inferior Fiber of Trapezius
Origin – spinous process of T6-T12
Insertion – spine of the scapula
Action scapular depression and adduction

30. Levator Scapulae
Origin – transverse process of Superior four or five cervical vertebrae.
Insertion – superior vertebral border of scapula
Action – Elevates scapula and rotates it downward.
Nerve supply – dorsal scapular nerve and cervical spinal nerve

31. Rhomboid Major Origin – Spine of 2nd to 5th thoracic vertebrae
Insertion – vertebral border of scapula inferior to spine of scapula
Action – elevates and adducts scapula and rotate it downward; stabilize scapula
Nerve – dorsal scapular nerve

32. Rhomboid Minor
Origin – Spine of 7th cervical and 1st thoracic vertebrae.
Insertion – Vertebrae border of scapula superior to spine
Action – elevates and adducts scapula and rotate it downward; stabilize scapula
Nerve – dorsal scapular nerve

33. Clavicle origin of Pectoralis Major
Origin – medial half of anterior clavicle
Insertion – greater tubercle and intertubercular sulcus of humerus
Action – Flexion, adduction and medial rotation arm at shoulder joint.
Nerve supply
Medial and lateral pectoral nerve

34. Sternal origin of Pectoralis Major
Origin – anterior surface of sternum, costal cartilage of 2nd -6th ribs.
Insertion – greater tubercle and intertubercular sulcus of humerus
Action – extend arm at shoulder joint.
Nerve supply
Medial and lateral pectoral nerve

35. Latissimus Dorsi
Origin – Spines of inferior 6 thoracic vertebrae (T6-T12), lumbar vertebrae (L1-L5), crest of sacrum and illiac crest of hip bone and inferior four ribs.
Insertion – Intertubecular sulcus of humerus
Action
Extends, adduction and medial rotation arm at shoulder joint.
Nerve supply - Thoracodorsal nerve

36. Latissimus Dorsi

37. Fiber of Deltoid Consists 3 fibers
Anterior, middle and posterior fibers.
Responsible for movements of the humerus at GH joint
Nerve supply – axillary nerve.

38. Anterior Fiber of Deltoid
Origin – anterior border of the lateral one third of the clavicle
Insertion – deltoid tuberosity
Action – flexion and middle rotation arm at GH joint.

39. Middle fiber of Deltoid
Origin – lateral border and superior surface of the acromion process of the scapula
Insertion – deltoid tuberosity
Action – abduction arm at GH joint

40. Posterior Fiber of Deltoid
Origin – inferior lip of the crest of the spine of the scapula
Insertion – deltoid tuberosity
Action – extension and lateral rotation arm at GH joint.

41. Rotator Cuff Muscles Consists 4 muscles S – Supraspinatus
I – Infraspinatus
T – teres minor
S – Subscapularis
Group of muscles that stabilize GH joint.

43. Supraspinatus Muscle Origin – supraspinous fossa of scapula
Insertion – Greater tubercle of humerus (anterior aspect)
Action – initially abduction (15 degrees) at shoulder joint, stabilizing shoulder joint
Nerve supply - Suprascapular nerve

44. Infraspinatus Muscle Origin – Infraspinous fossa of scapula
Insertion – Greater tubercle of humerus (posterior aspect)
Action – Laterally rotation and adduction arm at shoulder joint
Nerve supply - Suprascapular nerve

45. Teres Minor Origin – Inferior lateral border of scapula
Insertion – Greater tubercle of humerus (inferior aspect)
Action – Laterally rotation, extends and adduction arm at shoulder joint
Nerve supply – axillary nerve

46. Subscapularis Muscle Origin – subscapular fossa of scapula
Insertion – lesser tubercle of humerus
Action – Medial rotation arm at shoulder joint
Nerve supply – upper and lower subscapular nerve

47. Teres Major Origin – Inferior angle of scapula
Insertion – Intertubecular sulcus of humerus
Action
Extends arm at shoulder joint
Assist in adduction and medial rotation of arm at shoulder joint.
Nerve supply
Lower subscapular nerve

48. Coracobrachialis Origin - Coracoid process of scapula
Insertion - Middle of medial surface of shaft of humerus.
Action - Flexion and adduction arm at shoulder joint.
Nerve supply - Musculocutaneous nerve

49. Biceps Brachii
Consists 2 head
Long head and short head of biceps

50. Short head of Biceps Origin – Coracoid process of scapula
Insertion – radial tuberosity of radius
Action – Flexion forearm at elbow joint, flexion arm at GH joint and supination at radioulnar joint.
Nerve supply - Musculocutaneous nerve

51. Long head of Biceps
Origin – Tubercle above the glenoid cavity of scapula (supraglenoid tubercle)
Insertion – Radial tuberosity of radius
Action – flexion forearm at elbow joint, flexion arm at GH joint and supination forearm at radioulnar joint.
Nerve supply - Musculocutaneous nerve

52. Long head of Triceps
Origin – tubercle below to glenoid cavity of scapula (infraglenoid tubercle)
Insertion – Olecranon of ulna
Action - Extends forearm at elbow joint , Extends arm at shoulder joint
Nerve supply - Radial nerve
Posterior View

53. Sternomastoid / Cleidomastoid
Join together to form sternocleidomastoid muscle
Origin
(i) Sternomastoid - upper part of the anterior surface of the manubrium of sternum.
(ii) Cleidomastoid - superior border and anterior surface of the medial third of the clavicle.

54. Sternomastoid / Cleidomastoid
Insertion – Mastoid process of the mastoid portion of temporal bone.
Action - Acting together, flexes the neck, raises the sternum and assists in forced inspiration.
Nerve supply – accessory nerve (cranial nerve XI)

58. Force Couples at Scapulothoracic Joint
Serratus anterior produces antero-lateral movement of the inferior angle
Upper trapezius pulls scapula medially
Forces Couples for abduction
0-90° Deltoid and supraspinatus
° Trapezius (Upper and Lower), Serratus anterior, deltoid
° As above plus contralateral spinal muscles

59. Force Couple for Flexion
0-60° Anterior deltoid, coracobrachialis, pectoralis major
60-120° Trapezius (upper & lower), serratus anterior
° Lower trapezius, serratus anterior, contralateral spinal muscles

60. Scapular Rotation Phase 1
Upper & lower portions of trapezius & serratus anterior produce an upward rotatory force on the scapula
Motion at the A-C joint prevented by the oracoclavicular ligament
Rotation of the scapula occurs as elevation of the clavicle occurs at the S-C joint

61. Phase 1

62. Scapular Rotation Phase 2
Further motion at the S-C joint is prevented by the costoclavicular ligament
Continued upward rotation of the scapula pulls on the costo-clavicular ligament causing posterior rotation of the clavicle
Posterior rotation of the clavicle allows further rotation of the scapula

63. Phase 2

64. Scapular Rotation Necessary to: Enhance glenohumeral stability
Elevate acromion to avoid impingement
Maintain effective length tension relationship of scapulohumeral muscles