The shoulder girdle consists of three bones - the clavicle, scapula, and humerus. It contains four joints - the sternoclavicular, acromioclavicular, scapulothoracic, and glenohumeral joints. The glenohumeral joint is a ball and socket joint that allows for great mobility but also instability. During shoulder movements, the humerus, scapula, and clavicle move in coordinated patterns to provide both mobility and stability.

2. THE SHOULDER GIRDLE

3. Basic concepts about the Arthrokinematics of
shoulder girdle

4.  The shoulder girdle is the set
of bones which connects
the upper limb to
the axial skeleton on each side.
 Three synovial joints and a
functional articulations make
up the shoulder girdle
complex.
SHOULDER GIRDLE

5. SHOULDER GIRDLE
The shoulder girdle has only one
bony attachment to the axial
skeleton
 The clavicle articulates with the
sternum via the small
sternoclavicular joint.
 Stability is provided by an intricate
balance between the scapular and
glenohumeral muscles and the
structures of the joints in the
shoulder girdle.

11. Glenohumeral Joint
 “The shoulder is the most flexible joint in the body
making it the most susceptible to instability and injury.“
 Ball & socket joint with a lax joint capsule.

12. Glenohumeral Joint
It is supported by the tendons of the Rotator Cuff and
the Glenohumeral and Coraco-humeral & Transverse
Humeral ligaments.

13. Glenohumeral Joint
 The glenoid labrum (9mm thick), deepens the glenoid fossa for
greater congruity and serves as the attachment site for the capsule.
 Only a small portion of the head of humerus comes in contact with
the fossa, allowing for considerable humeral movement and
potential instability.

14. Joint surfaces
Capsulolabral complex
Ligaments
Rotator cuff
Scapular Stabilizer
Muscles
Mobility
Stability
Glenohumeral Joint

15. Normal range of motion of shoulder joint

16. Joint Arthrokinematics of the GH Joint
Pertaining to the movement of bone surfaces within a joint.

17. Joint Arthrokinematics of the GH Joint
Shoulder Flexion
 Head rolls in
the same
(anterior)
direction
 Slides in the
opposite
(posterior)
direction in the
glenoid fossa

18. Joint Arthrokinematics of the GH Joint
 Head rolls in
the same
(posterior)
direction
 Slides in the
opposite
(anterior)
direction in the
glenoid fossa
Shoulder Extension

19.  Shoulder
abduction
oHead rolls in the
same (superior)
direction
oSlides in the
opposite (inferior)
direction in the
glenoid fossa
Joint Arthrokinematics of the GH Joint

20. Joint Arthrokinematics of the GH Joint
 Head rolls in
the same
(inferior)
direction
 Slides in the
opposite
(superior)
direction in the
glenoid fossa
Shoulder adduction

21.  Internal
Rotation
oHead rolls in
the (anterior)
same direction
oSlides in the
opposite
(posterior)
direction in the
glenoid fossa
Joint Arthrokinematics of the GH Joint

22. Joint Arthrokinematics of the GH Joint
 Head rolls in
the (posterior)
same direction
 Slides in the
opposite
(anterior)
direction in the
glenoid fossa
External Rotation

23. Horizontal
abduction
Head rolls in the
same (posterior)
direction
Slides in the
opposite
(anterior)
direction in the
glenoid fossa
Joint Arthrokinematics of the GH Joint

24. Horizontal
Adduction
oHead rolls in
the (anterior)
same direction
oSlides in the
opposite
(posterior)
direction in the
glenoid fossa
Joint Arthrokinematics of the GH Joint

25. Acromioclavicular Joint
 The AC joint is a plane, triaxial joint
that may or may not have a disk. The
weak capsule is reinforced by the
superior and inferior AC ligaments.
 The convex bony partner is a facet on
the lateral end of the clavicle. The
concave bony partner is a facet on the
acromion of the scapula.
 The AC ligaments are supported by
the strong coracoclavicular ligament.
 No muscles directly cross this joint for
dynamic support.

26. Acromioclavicular Joint
Winging and tipping, seen with motion at the AC
joint concurrently with motions of the humerus
 Winging is a transverse plane motion where the
medial border lifts away from the rib cage; it
normally occurs with horizontal adduction of
the humerus.
 Forward tipping of the scapula occurs in
conjunction with internal rotation and
extension of the humerus when reaching the
hand behind the back.

27. Sternoclavicular Joint
 The sternoclavicular
(SC) joint is an
incongruent,
triaxial, saddle-
shaped joint with a
disk.
 The joint is
supported by the
anterior and
posterior SC
ligaments and the
interclavicular and
costoclavicular
ligaments

28. The motions of the clavicle occur as a result
of the scapular motions of elevation,
depression, protraction and retraction
Arthrokinematics

29. Arthrokinematics
Rotation of the clavicle occurs as an accessory motion when the
humerus is elevated above the horizontal position and the
scapula upwardly rotates

30. Normally there is considerable soft tissue flexibility,
allowing the scapula to slide along the thorax and
participate in all upper extremity motions.
Scapulothoracic Articulation

31. 
Motions of the Scapula

32. Motions of the Scapula

33. Motions of the Scapula
Protraction and retraction

34. Scapular Stability
 The weight of the arm creates a downward rotation, abduction, and forward
tipping moment on the scapula.
 The downward rotation is balanced by the dynamic support of the upper
trapezius and serratus anterior. The forward tipping and abduction is
balanced by the dynamic support of the rhomboids and middle trapezius.

35. Scapulohumeral Rhythm

36. Scapulohumeral Rhythm

37. Scapulohumeral Rhythm

38. Scapulohumeral Rhythm

39. The coracoacromial arch,
composed of the acromion and
coracoacromial ligament,
overlies the subacromial bursa &
supraspinatus tendon.
Faulty
o Muscle function
o Postural relationships
o joint mechanics
injury to the soft tissues or
structural anomalies
of the ACROMION lead to
impingement
Sub-acromial Space

45. Biglani et al, orthop trans, 1986

46. 46