The document discusses the scapulohumeral rhythm, which is the coordinated movement between the glenohumeral joint and scapulothoracic joint during shoulder movement. Specifically, it notes that for every 2 degrees of shoulder abduction or flexion, the scapula upwardly rotates approximately 1 degree. This ratio maintains proper shoulder range of motion and prevents impingement. Clinical issues like frozen shoulder and scapular winging can result from impairments affecting the scapulothoracic joint.

1. SCAPULOHUMERAL
RHYTHM
CHRISTOPHER JOHN

2. GLENOHUMERAL JOINT(GH)

3.  Glenohumeral joint is a ball
and socket joint with 3
degree of freedom.
 Since, Glenoid fossa of the
scapula is proximal segment
of glenohumeral joint, any
movement of scapula will
influence GH function

4. Scapulothoracic
joint
Scapulothoracic joint

5.  Scapulothoracic joint is formed by
articulation of scapula with thorax(ribs2-7)
 It is not a true anatomical joint rather it is
a functional joint.
 Movements :permits scapular
elevation/depression ,
protraction/retraction , upward/downward
rotation.
 Motion of ST joint is combined movement of
the Acromioclavicular(AC) and
Sternoclavicular(SC) joint.
 That is, the full 60° ST upward rotation=30°
of SC joint elevation+30° AC joint upward
rotation.

6. SCAPULOHUMERAL RHYTHM

7.  The full range of shoulder motion normally is
combination between the motion in Glenohumeral
and Scapulothoracic joint
 A natural rhythm/ratio between GH and
scapulothoracic joint is 2:1
 That is , for every 2° of shoulder abduction/flexion,
the scapula must upward rotate roughly 1°.(vice
versa for adduction/extension)
 The full ROM of shoulder abduction/flexion=180°,
which is a combination of 120° shoulder
abduction/flexion+60° scapular upward rotation.
 Without scapular rotation, the Humerus would not
be able to attain full ROM, it would be impinged
under the acromion.

8. Scapulothoracic Joint
Muscles
Primary elevators of ST joint
•Upper fiber of trapezius
• levator scapulae
•Rhomboids
Primary depressor of ST joint
•Lower fiber of trapezius
•Latissimus dorsi

10. Clinical aspects
Frozen shoulder
Frozen shoulder is a common condition in which the
shoulder stiffens, reducing its mobility.
mobility and flexibility exercises
Scapular winging
The term ‘winged scapula’ (also scapula alata) is used
when the muscles of the scapula are too weak or
paralyzed, resulting in a limited ability to stabilize the
scapula.

11. Reference
Joint structure
and function
Cynthia c .
Norkin
Physiopedia

12. Thank you