1. Shoulder Girdle-CH 9 Lenis J. Alicea-Yildirim PT, MEd Revision
William B. Young, PT
PT 110

2. Shoulder Complex…clarifications
Purpose to allow the hand to be placed in various positions to accomplish tasks.
The Shoulder Complex consist of
Shoulder girdle + Shoulder joint (glenohumeral joint)
Scapula, clavicle, sternum, humerus, rib cage, sternoclavicular joint, acromioclavicular joint, glenohumeral joint and “scapulothoracic articulation” (not a joint).
The scapula and the thorax do NOT have a point of fixation…they are connected indirectly by the clavicle and several muscles.

4. Shoulder Girdle… Term used to discuss the activities of : scapula
clavicle
sternum (lesser activity)
5 muscles that attach to scapula, clavicle or both to provide motion.
The sternoclavicular and acromioclavicular joints allow shoulder girdle motions:
Elevation/depression
Upward/downward rotation
Protraction/Retraction
Scapular tilt

5. Bones and Landmarks…
The scapula attaches to the trunk indirectly through its ligamentous attachment to the clavicle.
Scapula is slightly concave (anteriorly)
Glides over the convex posterior ribcage
Resting Position- is located between 2nd- 7th ribs
Vertebral body approximately 2-3 inches lateral from the spinous processes of the vertebra.
Many muscles also connect the scapula through the trunk

6. Resting position of the on the scapula on the thorax
Flat bone

7. Scapula... Superior angle Spine Inferior angle Coracoid process
Vertebral border
Acromion process
Axillary border
Glenoid fossa

8. Clavicle… S shape bone=long bone
Connects the upper extremity to the axial skeleton
Sternal End-Attaches medially to the sternum
Body- between the 2 ends
Acromial End-attaches laterally to the scapula

9. Sternum… Is a flat bone Midline of anterior thorax
Manubrium (superior end)- attachment for clavicle
Body (beneath)- attachment costal cartilages of the ribs
Xiphoid process(inferior tip)- “sword shape”

10. Joint and Ligaments…
Sternoclavicular-provides the shoulder girdle with the only direct attachment to the trunk
Synovial Joint
Double gliding motion
Plane shaped
3 planes of motion
Basically the clavicle moves while the sternum remains stationary

11. Sternoclavicular Joint…
Synovial Joint
Joint capsule
3 major ligaments
Costoclavicular Ligament-limits clavicular elevation
Interclavicular Ligament-limits clavicular depression
A & P Sternoclavicular Ligaments-provides reinforcement to the joint capsule
Articular Disk-shock absorber (outstretched hand injuries)
Dislocation is rare
Unique attachment- contribute to motion in this joint
During shoulder elevation/depression- motion between clavicle and disk
During protraction and retraction- motion occurs between disk and sternum

12. Sternoclavicular Joint
Ligaments of the sternoclavicular joint (left side cut away to show the disk).

13. Joint and Ligaments… Sternoclavicular joint
Capsular pattern- pain at extreme range
Loose packed position- arm resting by side
Closed packed position- maximum shoulder elevation

14. Acromioclavicular joint…
It’s a plane shaped synovial joint
3 planes of motion (minimal but important for normal shoulder motion)
Joint capsule surrounds the articular borders of the joint
Its weak joint and is reinforced above and below superior and inferior (S&I) acromioclavicular ligaments (3)

15. Acromioclavicular Ligaments… (3)
a) S & I Acromioclavicular ligaments- support/by holding the
acromion process to the clavicle and prevent dislocation
b) Coracoclavicular ligaments-med and lat portions
(accessory)
Its NOT directly located at the joint
Provides stability to this joint
Allows scapula to be suspended from the clavicle
Its divided into Lateral trapezoid and deeper medial conoid portion
Together they prevent backward motion of the scapula
Individually they limit the rotation of the scapula
c) Coracoacromial Ligament
Does NOT cross the acromioclavicular joint
Forms an arch over the head of the humerus (makes a roof)
Serves as a protective arch/support during upward forces

16. Ligaments… Ligaments of the Acromioclavicular Joint
The coracoacromial ligament forms a roof over the shoulder joint

17. Joint and Ligaments… Acromioclavicular joint
Capsular pattern- pain at extreme range
Loose packed position- arm resting by side
Closed packed position degrees Shoulder abduction

18. Joint Motions… Called shoulder girdle or scapular motion e.g.
Shoulder girdle protraction/retraction same as scapular abduction/adduction
The inferior angle is the point of reference (motion)

19. Shoulder Girdle Motions
Elevation and Depression
Protraction and Retraction
Upward and Downward Rotation
Scapular Tilt
“Wind up” or prerelease phase…
Shoulder hyperextension
pitching
swimming
bowling

20. Companion motions of the shoulder…
Upward rotation with shoulder flexion and abduction
Downward rotation with shoulder extension and adduction
Refer to pg 119

21. Scapulothoracic Rhythm
Describes movement relationship between shoulder girdle and shoulder joint.
First 30 degrees of shoulder motion is pure shoulder joint motion!
After that…for every 2 degrees of shoulder flexion or ABD the scapula must upwardly rotate 1 degree.
This is known as 2:1 scapulohumeral rhythm
e.g.
Try to move the shoulder while holding the axillary border of scapula to prevent rotation…

22. ANGLE OF PULL Several factors determine the role of a muscle
Major Role= Primer
Minor Role= Assisting Mover
No Role- due to size, angle of pull, possibility of motions or location of muscle to axis
Most muscles have a diagonal line of pull
Vertical angle of pull…up/down motion
horizontal- angle of pull-protracting/retracting
Or with more equal horizontal/vertical pull- both motions
e.g.
Levator Scapula- prime mover in scapula elevation
Middle Trapezius- prime mover in retraction of scapula
Rhomboids- prime mover in both elevation and retraction

23. BREAK

24. Muscles of the Shoulder Girdle… (5)
1. Trapezius
a) Upper trapezius
b) Middle trapezius
c) Lower trapezius
2. Levator Scapula
3. Rhomboids
4. Serratus Anterior
5. Pectoralis Minor

25. a) Upper Trapezius- (UT)
(O) Occipital protuberance and nuchal ligament of upper cervical vertebra
(I) lateral end of clavicle and acromion process
Line of more vertical than horizontal…is a prime mover in scapular elevation/upward rotation
Only assisting mover in retraction
All 3 parts work together (synergists) to retract scapula
Upper and lower portions are antagonist during elevation/depression
1.Trapezius
Large superficial muscle
Diamond Shaped
3 different lines of
pull

26. b) Middle Trapezius-
(O) Nuchal Ligament of lower cervical vertebrae and spinous process of C7 and upper thoracic
Line of Pull- horizontal
Prime mover-retraction
Assistive- scapular upward rotation
c) Lower Trapezius
(O) spinous processes of middle and lower thoracic vertebrae
(I) base of scapular spine
Line of pull- diagonal (more vertical)
Effective with depression and upward rotation

27. 2. Levator Scapula Muscle
Cover entirely by trapezius
Diagonal line of pull (vertical)
Prime mover in
Scapula elevation
Downward rotation
Assisting mover in retraction

28. 3. Rhomboids Major Minor Functionally same actions
2 muscles (but anatomical difficulty to separate)
Major
Minor
Functionally same actions
Lies under trapezius, but can be palpated when trapezius is relax
Oblique line of pull (horizontal and vertical)
Prime movers in retraction and elevation/downwardly rotate scapula

29. Serratus Anterior Muscle
(O) Lateral Surface of upper 8 ribs
(I)Vertebral border of scapula/anterior surface
Maybe palpated with hand over head (lateral side of thorax)
Near horizontal line of pull outward
Prime mover scapular protraction
Lower fibers effective in upwardly rotating scapula
They join the upper and lower trapezius muscles to form a force couple rotating the scapula upward
Absence results in “Winging of Scapula”

30. serratus anterior winging of scapula

31. Muscles pulling in different direction to accomplish the same motion
FORCE COUPLE
Muscles pulling in different direction to accomplish the same motion

32. upward rotation and downward rotation

33. 5.Pectoralis Minor Lies deep to pectoralis major muscle
The only shoulder girdle muscle located entirely on the anterior surface (3rd-5th ribs
Line of pull downward/mostly vertical
Prime mover scapular depression
Difficult to see downward rotation due to the muscle position (anterior surface)
Causes scapular tilt

34. Reversal Muscle Action
Muscle action of the shoulder girdle have been describe as moving insertion (I) toward the origin (O)
This allows some of the shoulder girdle muscles to have assistive roles in other joints
Head
Neck
e.g.
UT -on head and neck
Stabilized shoulder girdle
Assists in head/neck extension and laterally bending it to same side and rotating it to the opposite side.

35. Muscle Innervations… See table 9-2 and 9-3 Pg. 127 Nerves
Cranial Nerve XI
Dorsal scapular
*Long Thoracic
Medial Pectoral