FOR PHYSIOTHERAPY STUDENTS

1. SHOULDER COMPLEX – BIOMECHNICS
Dr.BHARTI PAWAR
(PT)

2. Anatomy
Shoulder Complex is Composed of
Clavicle
Scapula
Humerus & Joints that
link this bones together

3. JOINTS IN SHOULDER COMPLEX
Anatomic
⚫ Sterno Clavicular (SC)
⚫ Acromioclavicular(AC)
⚫ Glenohumeral (GH)
Functional
⚫ Scapulothoracic

4. SCAPULO THORACIC JOINT
⚫ Articulation of scapula with
thorax, depends on anatomic
SC & AC joints
⚫ Position of Scapula on post
thorax
 2 inches from midline &
from 2nd to 7th rib,
 Lies 30o
- 40o
forward plane
& is tipped anteriorly 10o
-
20o

5. MOVEMENTS IN SCAPULOTHORACIC JOINT
1. Elevation Depression
2. Protraction Retraction (Abduction/Adduction)
3. Upward & downward rotation
4. Anterior & Posterior Tipping

6. ANGLEOFINCLINATION&ANGLEOFTORTION
⚫ Angle of Inclination -Angle formed
by Intersection of axis through
humeral head & Longitudinal Axis
of shaft of Humerus - 130o
– 150o
⚫ Angle of Torsion – Formed between
Axis through axis through humeral
condyles & Axis through Humeral
head – 30o
posterior

8. STERNOCLAVICULARARTICULATION
⚫ IS Between two saddle shape surfaces, Synovial saddle jt, 30
Freedom
1) Sternal end of clavicle
2) Notch formed by manubrium of sternum & 1st costal cartilage
• Ends are invaribly congruent ( little contact between articular surfaces
& Concave convex at both articulating surfaces)

9. STERNOCLAVICULAR DISK
⚫ Superior portion of middle clavicle
does not contact manubrium instead
serves as attachment to joint disk &
interclavicular lig
⚫ Fibro cartilage joint disk is attached
superiorly to clavicle & lower portion
to the manubrium & 1st costal
Cartilage

10. FUNCTIONS OF STERNO CLAVICULAR DISK
Acts as pivot during SC motions
Upper end serves as pivot during Elevation-Depression &
lower end during protraction- retraction
 Stability by increasing joint congruency, Shock Absorption
Absorbs medially directed forces from lat end of clavicle
Unique diagonal attachment prevents clavicle to override
shallow manubrium facet

11. STERNOCLAVICULAR JOINT MOTIONS
KINEMATICS
 3o
freedom
1. Elevation ( 45o
) Depression (15o
)
2. Protraction (15o
) Retraction (15o
)
3. Anterior (0o
- 5o
) Posterior rotation (25o
- 55o
)
 During Elevation & Depression disk remains stable
 During protraction & retraction disk moves along with
clavicle

12. A. Elevation & Depression
⚫ A- P / Saggital Axis & Frontal
Plane
⚫ During elevation middle clavicle
surface slides downwards on
mnubrium & during depression it
slide upwards
⚫ Evelation & Depression of
Clavicle is associated with
elevation & depression of scapula

13. B. Protraction & Retraction
⚫ Vertical Axis & Transverse
Plane
⚫ During Protraction &
Retraction articular disk
moves along with the clavicle
⚫ Medial surface of clavicle
moves in same direction of lat
end of clavicle

14. C. Ant-Post/Upward-downward rotation of clavicle
⚫ Longitudinal Axis , Saggital plane
⚫ Rotation occurs as spin between saddle shaped surface of clavicle &
manubriocostal facet with scapular rotation movts
⚫ During post(upward) rotation inferior surface of clavicle faces anteriorly
⚫ upward rotation of scapula will lead to posterior rotation of clavicle

15. LIGAMENTS – KINETICS
⚫ Capsule all around
⚫ Inter clavicular lig checks excessive
depression
⚫ Anterior & Posterior sternoclavicular
lig (checks Protraction & Retraction)
⚫ Costocalvicular lig Provides inferior
stability & counter balance superiorly
directed forces

17. ACROMIO-CLAVICULAR JOINT
Plane Synovial 3o
of Freedom
⚫ Articulation between Lateral end
of clavicle with acromion process
(Reciprocally Concave Convex or
reverse)

18. ACROMIO-CLAVICULAR JOINT conti…
⚫ Inclination of articulating surfaces
varies individual to individual
hence arthrokinematis is
unpredictable
⚫ Function – Maintain relation
between clavicle and scapula
during movements of shoulder
joint

19. MOVEMENTS IN AC JOINT
occurs with movements of Scapula
⚫ Anterior & Posterior Tipping
⚫ Upward & downward rotation
⚫ Elevation of upper arm (Jointly occurs with ant tipping &
Posterior rotation of Clavicle)

20. Ligaments
⚫ AC disk Variable in size &
differs among individuals,
various times in life, between
sides of same individual
⚫ Separates articulating
surfaces & Acts as pivot
point

21. Ligaments
⚫ AC Ligament is composed of parallel
fibers gives horizontal stability
⚫ CC Ligament firmly unites clavicle &
scapula, Rotatory stability
1. Trapezoid part (Lat & Quadrilateral
in shape)
2. Conoid Part(Med & Post to
trapeziod, Tringular in shape)

22. SCAPULOHUMERALRHYTHM
⚫ Coordinated motion of scapula and
humerus experienced during
shoulder movement
⚫ Ratio of 2:1 (2 degrees of humeral
flexion/abduction to 1 degree of
scapular upward rotation)

23. GLENOHUMERAL JOINT
Synovial Joint Ball & Socket Variety , 3o of Freedom
 Articulating Surface
o Glenoid fossa
o Head of Humerus

24. SUPPORTING STRUCTURES OF GH JOINT
⚫ Glenoid Labrum
⚫ Joint Capsule
⚫ Glenohumeral Ligament (Sup,
Middle, Inferior GH Lig)
⚫ Coraco acromial Ligament
⚫ Surrounding Musculature

25. GLENOID LABRUM
⚫ Fold of Dense fibrous
connective tissue with little fibro
cartilage
⚫ Attached periphery of glenoid
fossa enhancing depth &
curvature of fossa

26. GLENOID LABRUM CONTI……..
⚫ Superiorly it is loosely attached &
inferior portion is firmly attached &
relatively less mobile
⚫ When Arm is resting independently at
side two articulating surfaces has very
little contact & posterior head rest only
on small inferior portion of fossa

27. GLENOHUMERAL JOINT CAPSULE
⚫ Capsule is twice the size of humeral
head
⚫ In loose pack position it allows 1
inch of dislocation of head from
glenoid fossa
⚫ In resting position capsule is taught
superiorly & lax inferiorly

28. GLENOHUMERAL JOINT CAPSULE Conti…
⚫ Capsule is supported
o superiorly by –Coracohumeral lig
o Anteriorly by – 3 GH lig
o Posteriorly by rotator cuff

30. GLENOHUMERAL LIGAMENTS
⚫Superior GH Lig
⚫Middle GH Lig
⚫Inferior GH Lig
⚫Coracohumeral Lig
⚫Coracoacromial Lig
⚫Transverse Humeral Lig

31. BURASAE IN SHOULDER JOINT
⚫ Subacromial Bursa (Permits
Smooth gliding of
Supraspinatus & head of
Humerus)
⚫ Subdeltiod Bursa ( Smooth
gliding of Deltoid & Acromion
Process)

32. BURASAE IN SHOULDER JOINT
 Subcoracoid Bursa
⚫ Functions –
 Reduce friction between
coracobrachialis, subscapularis &
short head of biceps tendons, thus
facilitating internal & external
rotation of shoulder.
Subsscapular Bursa
Reduces Friction of superficial fibers against scapular neck,
humeral head & coracoid process.

33. CORACOACROMIALARCH
When suprahumeral space is narrowed impingement of supraspinatus tendon
&subacromian bursa increases& causes painful supraspinatus impingement syndrome
Formed by coracoid process,Acromion & Croraco-acromial lig (Osteoligaments vault)
⚫ Structures bet arch are subacromiom
bursa& supraspinatus tendon , Portion of
Long head of biceps
⚫ Functions-
⚫ Prevents superior disloccation of head of
humerus

34. MUSCLES
Flexors
⚫ Deltoid
⚫ Pectoralis Major
⚫ Short head of Biceps
⚫ Coracobrachailis
Extensors
⚫ Teres Major
⚫ Long head of Triceps
⚫ Latisimus Dorsi

35. MUSCLES
Abductors
Adductors
⚫ Teres Major
⚫ Pectoralis Major
⚫ Short head of Biceps
⚫ Long Head of Triceps
⚫ Coracobrachlis
⚫ Supraspinatus
⚫ Deltoid
⚫ Serratus Anterior
⚫ Upper & Lower fibers of
Trapezious

36. MUSCLES
Medial Rotators
⚫ Deltoid ant Fibers
⚫ Pectoralis Major
⚫ Latisimus Dorsi
⚫ Teres Major
Extensors
⚫ Deltoid Post Fibers
⚫ Infraspinatus

37. KINEMATIS OF GLENOHUMERALJT
 Osteokinamatics
 Flexion Extention
• Frontal Axis, Saggital Plane
• Flex-120o (GH) + 60o(ST) = 180o
• Exten-50o – 60o

38. KINEMATIS OF GLENOHUMERALJT CONTI….
 Osteokinamatics
 Abduction Adduction
• Saggital Axis, Frontal Plane
• Abduc-120o (GH) + 60o(ST) = 180o
• Adduc- 120o - 0o
• Medial Lateral Rotation
• Vertical Axis, Horizontal Plane
• MR-70o, LR- 90o

39. ⚫ Arthrokinematics
⚫ Concave Convex Rule – (Glenoid
fossa is Concave & Humeral
Head is Convex)
⚫ Convex head is substantially
larger surface & has different
radius of curvature then shallow
concave fossa
KINEMATIS Conti…

40. ⚫ Arthrokinematics Conti…..
⚫ During Abduction Movement-
Superior rolling & Translation
& Inferior gliding occurs
⚫ Humeral head is translated 1-
2mm superiorly during elevation
of arm
KINEMATIS Conti…

41. Arthrokinematics Conti…
⚫ Abduction ( 120o+ 60o =180o)
⚫ Restriction to abduction is caused by
impingement of greater tubercle on
coracoacromial arch ( at 90o abduct)
Hench humerus is laterally rotated 35o
- 40o so greater tubercle will pass
under or behind arch & further
abduction can be continued without
impingement

43. KINETICS LIGAMENTS
⚫ Superior GH Lig originates from
anterior superior labrum & inserted
on lesser tuberosity
⚫ Function- Primary restrain to
inferior translation of adducted
shoulder at neutral position , MGH
Lig & IGH lig are lax in this
position

44. Ligaments conti..
⚫ Middle GH Lig originates from anterior
superior labrum, Supra glenoid tubercle
& inserted on lesser tuberosity
⚫ Function-
o Primary restrain to inferior translation
when arm is abducted & ex rotated.
o Restrain anterior translation having its
maximumal exffect when arm abducted
45o

45. ligaments conti..
⚫ Inferior GH Lig originates from
inferior labrum & inserted on
anatomic neck of humerus
1) Anterior Band
2) Posterior Band
3) Axillary band

46. ligaments conti..
⚫ Functions-
o Primary restrain to anterior& inferior
translation when arm is abducted 90o
o Ant band restrains anterior translation
when arm is abducted & externally
rotated
o Post band restrains posterior
translation when arm is abducted and
internally rotated

47.  Coracohumeral Lig
⚫ Originates from coracoid process & has
two bands – One insreted on lesser
tubercle –Second inserted on greter
tubercle
⚫ Long head of biceps passes through
tunnel between this two bands
⚫ Functions:
⚫ Inferior translation of Humeral head

48. kinetics conti…
⚫ Stability of shoulder joint is
provided by static & Dynamic
structures
⚫ Static stabilizers are passive
structures & dynamic are
musculature surrounding
shoulder joint

49. STATIC STABILITY
⚫ In resting position humeral head is not in contact with glenoid
fossa or it rest on inferior glenoid fossa
⚫ Gravity acts on humerus parrellal to shaft in downward
direction
⚫ This could require a verticle upward pull to restore equilibrium

50. Static Stability Conti….
⚫ Such vertical force could only be supplied by muscles such
as deltoid, long head of biceps & triceps.
⚫ Muscles are electrically silent in relax unloaded position
hence gravity is offset by a force that can apply a torque of
equal magnitude in opposite direction and this force is
genarated by static stabilizers

51. STATIC STABILIZERS
⚫ Articular Incongruence - Glenoid Fossa, Angle of inclination &
Torsion
⚫ Glenoid Labrum by incresing depth by 50%, Suction effect &
Adsive cohessive forces
⚫ Joint Capsule by Intracapsular Pressure
⚫ Ligaments ( SGH,MGH,IGH)
⚫ Joint Cohesion
⚫ Intra-articular negative Pressure

52. DYNAMIC STABILIZERS
 DELTOID FORCE COUPLE
 In neutral position deltoid has small angle of
application/Moment arm for abduction as
compare to supraspinatus & line of pull is
directed superiorly
 Hence force generated by middle deltoid tends
to produce superior translation of head on
glenoid fosssa rather than abduction rotation

53. SUPRASPINATUS FORCE COUPLE
⚫ In neutral position abduction moment of supraspinatus is slightly greater
than deltoid
⚫ Hence in initial abduction Supraspinatus has mechanical advantage and its
contraction trends to produce abduction while simultaneously compressing
GH joint
Dig shows line of action of Supraspinatus

54. Conti
…..
⚫ However physiological cross section areas of supraspinatus is smaller
than that of deltoid and consequently supraspinatus is incapable of
generating large abduction moments
⚫ Hence further Powerful abduction requires simultaneous activity of
both deltoid & supraspinatus

55. DELTOID & INFRSPINATUS, TERES MINOR &
SUBSCAPULARIS FORCE COUPLE
⚫ Unrestricted superior glide of humeral head
results in compression of contents of
subacromial space
⚫ Hence when deltoid contracts all rotator
muscles are also initiated and contracts to exert
compressive force on proximal humerus
holding head of humerus firmely against
glenoid fossa
⚫ Simultaneously teres minor lower portion of
infraspinatus & subscpularis apply inferior
force on humeral head giving additional
stability/protection against superior glide of
humerus
Dig shows line of action of SIT

56. Conti…
⚫ Contraction of SIT with deltoid forms an anatomical force
couple in which upward and downward full of muscles are
balances and forces contribute to abduction
⚫ Thus abduction & Elevation of arm depends on 3 factors
1) Deltoid full
2) Supraspinatus full
3) SIT full

57. SUMMARY OF DYNAMIC
STABILIZATION
 Deltoid provides strength to the
movement
 Supraspinatus provides mechanical
advantage early in ROM
 Rest of Rotattor cuff provides joint
compression throughout ROM
 SIT provides stability to humeral head
in inferior direction
 Lost of any of this results in significant
impairment in ability to elevate
shoulder