pathomechanics of shoulder joint, clinical significance of shoulder muscle, axiohumeral muscles, scapulohumeral muscles,

1. PATHOMECHANICS OF GLENOHUMERAL
JOINT
PRESENTED BY : - SYED ADIL
[MUSCULOSKELETAL PHYSIOTHERAPY]
DEPARTMENT

2. SCAPULOHUMERAL MUSCLES
 DELTOID - [ANT, MID, POST]
 SUPRASPINATUS
 INFRASPINATUS
 SUBSCAPULARIS
 TERES MINOR
 TERES MAJOR

3. DELTOID

4. ANTERIOR DELTOID
ACTION
 SHOULDER FLEXION
 HORIZONTAL ADDUCTION

5. • WEAKNESS of the anterior deltoid muscle is likely to produce weakness in
shoulder flexion.
• However, weakness may also result in diminished strength of shoulder,
shoulder abduction, and horizontal adduction.
• TIGHTNESS of the anterior deltoid can contribute to diminished shoulder
extension and lateral rotation ROM

6. POSTERIOR DELTOID
ACTIONS
SHOULDER EXTENSION
HORIZONTAL ABDUCTION

7. • EFFECT OF WEAKNESS OF THE Posterior Deltoid Include decreased
shoulder extension strength.
• EFFECT OF TIGHTNESS of the posterior deltoid include restricted
shoulder flexion and horizonal adduction ROM.

8. MIDDLE DELTOID – [ACTION : ABDUCTION]
• Loss of the middle deltoid weakens, but does not eliminate, active
abduction of the shoulder
• It is unlikely that tightness of the middle deltoid muscle actually can
restrict shoulder adduction ROM.
• However, the position of shoulder adduction applies tension to the
middle deltoid and may cause pain or additional disruption to the
tendon of the deltoid or the bursa lying deep to it.

9. SUPRASPINATUS –
ACTIONS
 ABDUCTION
 DYNAMIC STABILIZATION

10. • The supraspinatus muscle is the most superior muscle of the rotator
cuff group.
• It lies deep to the subacromial (subdeltoid) bursa, the coracoacromial
ligament, and the deltoid muscle and acromion process.
• The supraspinatus muscle participate specifically in stabilizing the
glenohumeral joint in the inferior direction (dynamic stabilizer)

11. • The supraspinatus helps stabilize the glenohumeral joint by exerting a
horizontal pull to hold the humeral head against the glenoid process.

12. INFERIOR SUBLUXATION OF
GLENOHUMERAL JOINT

13. The proposed function of the supraspinatus in preventing the inferior subluxation
of the glenohumeral joint is facilitated by the upward tilt of the glenoid fossa
Weakness of the trapezius may contribute to inferior subluxations of the joint.
(example upper extremity weakness following stroke)
Thus the inferior subluxation of the glenohumeral joint may be the result of the
combined effects of weakness of the supraspinatus and trapezius muscles

14. • Thus, treatment approaches should include exercises to restore an
upward tilt of the glenoid fossa while facilitating the activity of the
rotator cuff muscles (supraspinatus)

15. WEAKNESS OF THE SUPRASPINATUS MUSCLE can result from :-
1. Denervation secondary to an entrapment of the suprascapular nerve
2. Mechanical disruption of the muscle’s tendon or its insertion into the
glenohumeral joint capsule
3. Inhibition of muscle contraction caused by pain secondary to such
disorders as tendinitis

16. • WEAKNESS of the supraspinatus is manifested by a significant
decrease in the strength and endurance of shoulder abduction
• TIGHTNESS of the supraspinatus tendon is unlikely, but it can be
present following surgical repair of a rotator cuff tear.

17. INFRASPINATUS
ACTION
 LATERAL ROTATION
 HORIZONTAL ABDUCTION
 STABILIZATION

18. • Isolated WEAKNESS of the infraspinatus is unusual but has been
reported. It is manifested clinically by a significant reduction in the
strength of lateral rotation of the shoulder.
• Tightness of the infraspinatus contributes to decreased ROM of shoulder
medial rotation and may also contribute to decreased horizontal
adduction ROM.

19. TERES MINOR
ACTION
LATERAL ROTATION
ADDUCTION
STABILIZATION

20. • Weakness of the teres minor can contribute to a decrease in the
strength of shoulder lateral rotation.
• However, since the physiological cross-sectional area of the teres
minor is so much smaller than that of the other lateral rotators, the
decrease in lateral rotation strength is unlikely to be significant.

21. SUBSCAPULARIS
ACTION
INTERNAL ROTATION
ADDUCTION
STABILIZATION

22. • WEAKNESS of the subscapularis results in a significant decreasein
strength of shoulder medial rotation.
• Weakness of the subscapularis may also contribute to anterior
instability of the glenohumeral joint.

23. CLINNICAL RELAVANCE
• SUBSCAPULARIS WEAKNESS: Decreased activation of the subscapularis
is reported in some individuals who can sublux their glenohumeral joints
spontaneously using lateral rotation.
• Muscle re-education to facilitate the subscapularis and other medial
rotators is an important component of the rehabilitation program to
increase stability.

24. • TIGHTNESS of the subscapularis causes decreased lateral rotation ROM
at the shoulder.
• Tightness of the subscapularis muscle sometimes is induced deliberately
to improve joint stability surgically in individuals with chronic anterior
dislocations of the glenohumeral joints

25. TERES MAJOR
ACTION
ADDUCTION
INTERNAL ROTATION

26. • The teres major exhibits EMG activity with the
shoulder held in static positions of flexion or
abduction and it is is also able to pull on the
scapula when the humerus is held fixed.
• Thus, the teres major assist in stabilizing the
scapulothoracic joint rather than to move or
hold the glenohumeral joint.

27. • The tightness can also influence the
resting position and mobility of the
scapulothoracic joint.
• It can pull the scapula into a position of
abduction and upward rotation,
contributing to another variant of the
rounded-shoulders posture.
TIGHTNESS of the teres major can be expected to result in restricted ROM in
shoulder lateral rotation, flexion, and abduction.

28. -: SUMMARY :-
SCAPULOHUMERAL MUSCLES
RESTRICTED
ROM
DYNAMIC
STABILITY

29. AXIOHUMERAL MUSCLES
 PECTORALIS MAJOR
 LATISSIMUS DORSI

30. PECTORALIS MAJOR
• The pectoralis major has two
distinct bellies, a smaller
clavicular portion and a
much larger sternal portion

31. ACTIONS :-
 SHOULDER FLEXION (CLAVICULAR FIBRES)
 SHOULDER EXTENSION FROM FLEXED POSITION
(STERNAL FIBRES)
 MEDIAL ROTATION
 SHOULDER DEPRESSION
 RESPIRATION

33. • WEAKNESS of the whole pectoralis major may result in decreased
strength in medial rotation, adduction, horizontal adduction of the
shoulder, and shoulder depression.
• TIGHTNESS of the pectoralis major is likely to restrict shoulder
abduction and flexion ROM as well as lateral rotation ROM of the
shoulder.

34. LATISSIMUS DORSI
ACTIONS
 EXTENSION
 ADDUCTION
 MEDIAL ROTATION
 SHOULDER DEPRESSION
The latissimus dorsi is a broad flat muscle with an extensive
attachment on the spine and pelvis, suggesting that this
muscle is capable of generating large forces

35. CLINICAL RELEVANCE
LATISSIMUS DORSI PEDICLE FOR RECONSTRUCTIVE SURGERY:
• Because of its size and vascular supply from multiple arteries, the
latissimus dorsi is a frequent source of grafting material for
reconstructive surgery, including wound closures and breast
reconstruction.
• Such surgery can significantly impair the strength of the shoulder from
which the latissimus dorsi is taken

36. • The latissimus dorsi is an important muscle in swimming and is very
strong and perhaps overdeveloped in competitive swimmers.
• TIGHTNESS of the latissimus dorsi limits shoulder ROM in flexion, lateral
rotation, and perhaps abduction.
• Consequently, tightness of the latissimus dorsi also may contribute to
flexion of the upper thoracic spine i.e. a tight latissimus dorsi may
contribute to increased thoracic kyphosis.

37. SHOULDER DEPRESSION
• The force of shoulder depression is particularly
important when the upper extremity is used in
weight-bearing activities. For example, as a person
uses a cane, the arm is bearing weight. The reaction
force of the cane tends to elevate the shoulder.
• Active contraction of the shoulder depressors
stabilizes the shoulder, preventing elevation.

39. Thank you 