The Shoulder
Complex
The Shoulder Complex
A.
B.
C.
D.
E.
General Structure & Function
Structure & Function of Specific Joints
Muscular Considerations
Specific Functional Considerations
Common Injuries
The Shoulder Complex
A.
B.
C.
D.
E.
General Structure & Function
Structure & Function of Specific Joints
Muscular Considerations
Specific Functional Considerations
Common Injuries
General Structure
General Function
 Provides very mobile, yet strong base for
hand to perform its intricate gross and
skilled functions
 Transmits loads from upper extremity to
axial skeleton
Shoulder Girdle
Shoulder Complex Movements
 Shoulder Girdle




Elevation & depression
Protraction & retraction
Upward & downward rotation
Upward tilt
 Shoulder (glenohumeral)



FL, EXT, HyperEXT
ABD, ADD, HyperADD, HyperABD
MR, LR, HorizontalABD, HorizontalADD
Abduction/Lateral Tilt
(Protraction)
Linear Movement
Frontal Plane
Angular movement
Transverse Plane
Adduction/Reduced
Lateral Tilt
(Retraction)
Depression
Elevation
Linear Movement
Frontal Plane
Downward rotation
Upward rotation
Shoulder Complex Movements
Upward tilt
Reduction of
Upward Tilt
Angular movement
Sagittal plane
Limited by capsular
torsion
Limited by bony
impingement of
greater tubercle on
acromion
Large ROM Due To:
 Poor bony structure
 Poor ligamentous restraint
 Scapulohumeral cooperative action
The Shoulder Complex
A.
B.
C.
D.
E.
General Structure & Function
Structure & Function of Specific Joints
Muscular Considerations
Specific Functional Considerations
Common Injuries
Structure & Function of
Specific Joints
1.
2.
3.
4.
5.
Sternoclavicular Joint
Acromioclavicular Joint
Scapulothoracic Joint
Glenolhumeral Joint
Coracoacromial Arch
Sternoclavicular Joint:
Bony Structure
Poor
Diarthrodial Biaxial
Sternoclavicular Joint:
Capsule
Very strong
Sternoclavicular Joint:
Interclavicular Ligament
Resists superior
& anterior
(posterior
portion) motion
Sternoclavicular Joint:
Sternoclavicular Ligament
Resists anterior
(PSL), posterior
(ASL), &
superior motion
Sternoclavicular Joint:
Costoclavicular Ligament
Resists upward
and posterior
motion
Sternoclavicular Joint:
Accessory Structures
Resists medial
& inferior
displacement
via articular
contact
Sternoclavicular Joint: Articular
Surfaces
Medial end of clavice
is convex
Clavicular facet is
reciprocally shaped
Sternoclavicular Joint: Motions
Axial Rotation: 50°
EL/DEP:
35°
PROT/RET:
35°
Sternoclavicular Joint: Motions
Frontal plane
Elev/Dep
Sagittal plane
Post Rot
Horizontal plane
ProT/ReT
Ant/Post axis
Vertical axis
Acromioclavicular Joint
Bony Structure
Poor
Diarthrodial Nonaxial
Acromioclavicular Joint:
Joint Capsule
Very weak
Acromioclavicular Joint
Acromioclavicular Ligament
Resists axial
rotation &
posterior motion
Acromioclavicular Joint
Coracoclavicular Ligament
Resists superior
motion
Acromioclavicular Joint
Accessory Structures
Articular disc
Acromioclavicular Joint:
Motion
Little relative
motion at AC joint
UR/DR:
EL/DEP:
PROT/RET:
60°
30°
30-50°
Acromioclavicular Joint:
Osteokinematics
Horizontal plane
adjustments
during scapulothoracic
protraction
Sagittal plane adjustment
during scapulothoracic
elevation
Clavicle
 Acts a strut connecting upper extremity
to thorax
 Protects brachial plexus & vascular
structures
 Serves as attachment site for many
shoulder muscles
Scapula
Scapular Plane
Scapulothoracic Joint
 No osseous
connection
 SUBSCAP & SA
Glenohumeral Joint:
Humerus
Retroversion angle: 30°
Glenohumeral Joint:
Humerus
Inclination angle: 45°
Glenohumeral Joint:
Glenoid Fossa
 Inclination angle: 5°
 Retroversion angle: 7°
Glenohumeral Joint:
Glenoid Fossa
 Articular cartilage
thicker on periphery
 Shallow fossa 1/3
diameter of humeral
head
Glenohumeral Joint:
Bony Structure
 Pure rotation
 Bony restraint poor
 Head 4-5X larger than
fossa
 Close-packed position

ABD with LR
Glenohumeral Joint:
Joint Capsule
 Inherently lax
 Surface area 2X
head
 Provides restraint for
ABD, ADD, LR, MR
Glenohumeral Joint:
Superior GH Ligament
 Resists inferior
translation in rest or
adducted arm
 Well-developed in
50%
Glenohumeral Joint:
Coracohumeral Ligament
 Resists inferior
translation in
shoulders with lessdeveloped SGH
Glenohumeral Joint:
Middle GH Ligament
 Great variability in
proximal attachment &
morphology
 Absent in 30%
 Resists inferior
translation in ABD &
ER
 Restrains anterior
translation (45° ABD)
Glenohumeral Joint:
Inferior GH Ligament
 3 components (A,P,Ax)
 Resists inferior,
anterior, & posterior
translation
Glenohumeral Joint: Bursae
 Subcoracoid
 Subacromial
 Subscapular
Glenohumeral Joint:
Accessory Structures
Labrum
 50% of depth
 Increases tangential stability 20%
Glenohumeral Joint:
Intra-articular Pressure
 Synovial fluid causes
adhesion
 Provides ~50%
restraint
Coracoacromial Arch
Glenohumeral Joint: ROM
 Flexion (167° W; 171° M)

30° in max LR
 Extension (60°)
 Abduction (180°)

60° in max IR
 Hyperadduction (75°)
Glenohumeral Joint: ROM
 Medial rotation (90°)
 Lateral rotation (90°)
 Total rotation
180°
 Total ROT 90° in
90° ABD
 Horizontal abduction (45°)
 Horizontal adduction (135°)
Role of multiarticular muscles???
Soft Tissue Restraint
Summary
 Anterior






Capsule
Labrum
Glenohumeral lig
Coracohumeral lig
Subscapularis
Pectoralis major
 Inferior


Capsule
Triceps brachii (L)
 Posterior




Capsule
Labrum
Teres minor
Infraspinatus
 Superior






Labrum
Coracohumeral lig
Suprapinatus
Biceps brachii (L)
Coracoacromial arch
Subacromial bursa
The Shoulder Complex
A.
B.
C.
D.
E.
General Structure & Function
Structure & Function of Specific Joints
Muscular Considerations
Specific Functional Considerations
Common Injuries
Shoulder girdle has its own set of muscles.
Retraction of the Scapulothoracic Joint
Levator scapula
Protraction of the Scapulothoracic Joint
Pectoralis minor
Pathomechanics of a weak
serratus anterior muscle
Deltoid force causes scapula to downwardly rotate.
Unstable and cannot resist deltoid force
GH Flexion
 Prime flexors:


Anterior deltoid
Pectoralis major: clavicular portion
 Assistant flexors:


Coracobrachialis
Biceps brachii: short head
GH Extension
 Gravitational force
 Posterior deltoid
 Latissimus dorsi
 Pectoralis major (sternal)
 Teres major (with resistance)
Abduction at Glenohumeral
Joint
 Major abductors of humerus:

Supraspinatus
 Initiates
abduction
 Active for first 110 degrees of abduction

Middle deltoid
 Active
90-180 degrees of abduction
 Superior dislocating component neutralized
by infraspinatus, subscapularis, and teres
minor
Adduction of Glenohumeral
Joint
 Primary adductors:



Latissimus dorsi
Teres major
Sternocostal pectoralis
 Minor assistance:



Biceps brachii: short head
Triceps brachii: long head
Above 90 degrees- coracobrachialis and
subscapularis
GH Medial Rotation
 Subscapularis
 Latissimus dorsi
 Pectoralis major
Decreased activity
with ABD
 Teres major (with resistance)
GH Lateral Rotation
 Primary

Infraspinatus
 Assistant:


Teres minor
Posterior deltoid
Horizontal Adduction and
Abduction
 Anterior to joint:


Pectoralis major (both heads), anterior
deltoid, coracobrachialis
Assisted by short head of biceps brachi
 Posterior to joint:


Middle and posterior deltoid, infraspinatus,
teres minor
Assisted by teres major, latissimus dorsi
Muscle Strength
 Adduction (2X ABD)
 Extension
 Flexion
 Abduction
 Internal rotation (max in neutral)
 External rotation (max at 90° FL)
Role of multiarticular muscles???
The Shoulder Complex
A.
B.
C.
D.
E.
General Structure & Function
Structure & Function of Specific Joints
Muscular Considerations
Specific Functional Considerations
Common Injuries
Specific Functional
Considerations
 Stability Functions of Shoulder Girdle
 Mobility Functions of Shoulder Girdle
 Rotator Cuff Function
Stability Functions of Shoulder
Girdle
 Provides stable base from which
shoulder muscles can generate force



Shoulder girdle muscles as stabilizers
Maintain appropriate force-length
relationship
Maintain maximum congruence of shoulder
joint
Specific Functional
Considerations
 Stability Functions of Shoulder Girdle
 Mobility Functions of Shoulder Girdle
 Rotator Cuff Function
Mobility Functions of Shoulder
Girdle
 Permits largest ROM of any complex in
the body


Shoulder girdle increases ROM with less
compromise of stability (scapulohumeral
rhythm) (4 joints vs. 1 joint)
Facilitate movements of the upper
extremity by positioning GH favorably
Dynamic Stabilization
Mechanisms
 Passive muscle tension
 Compressive forces from muscle
contraction
 Joint motion that results in tightening of
passive structures
 Redirection of joint force toward center
of GH joint
Muscular Considerations
 Force-length relationships quite variable
due to multiple joints
 Tension development in agonist
frequently requires tension development
in antagonist to prevent dislocation of the
humeral head
 Force couple – 2 forces equal in
magnitude but opposite in direction
Movements in the Frontal Plane
GH Joint - Abduction
ABD - 60°
 Shoulder Girdle: UR
 Totals


UR - 20°
Upward rotation - 60°
GH Abduction - 120°
 2:1 (.66) ratio
ABD - 30°
 1.25:1 after 30°
UR - 40°
 0.5-0.75 across
individuals
ABD
30°
Movements in the Frontal Plane
GH Joint - Adduction
 Shoulder Girdle: DR
Fig 5.17
Movements in the Sagittal Plane
GH Joint – Flexion & Extension
 Shoulder Girdle:




UR
ELEV (>90°)
PROT ( to 90°)
RET (>90°)
Fig 5.18
Movements in the Sagittal Plane
GH Joint - Hyperextension
 Shoulder Girdle: Upward tilt of scapula
Fig 5.20
Movements in the Transverse Plane
GH Joint – MR & LR
Fig 5.22a
Spinal Contribution to GH Motion
Movements in the Transverse Plane
GH HAdd & HAbd
Large ROM Due To:
 Poor bony structure
 Poor ligamentous restraint
 Scapulohumeral coordination
 Normal movement dependent on
interrelationships of 4 joints
 Restriction in any of these four can
impair normal function
Specific Functional
Considerations
 Stability Functions of Shoulder Girdle
 Mobility Functions of Shoulder Girdle
 Rotator Cuff Function
Supraspinatus
Teres minor
Subscapularis Infraspinatus
Function of Rotator Cuff
 Large external
muscles (e.g., lats,
delts) create shear
forces
 Rotator cuff provides


Joint compression
Tangential restraint
(Ant, Post, Sup)
Destabilizing Action of Deltoid
Deltoid produces superior shear force at GH joint.
Subscapularis
 Resists superior
shear
 Produces
simultaneous internal
rotation
Infraspinatus & Teres Minor
 Resists superior
shear
 Neutralizes
SUBSCAP internal
rotation
Supraspinatus
Summary of Active
Arthrokinematics Resisting Shear
Destabilizing Action of
Latissimus Dorsi
 LD pulls humerus
INF
 SSP resists INF
force
 INF & SUBSCAP
create compressive
force
The Shoulder Complex
A.
B.
C.
D.
E.
General Structure & Function
Structure & Function of Specific Joints
Muscular Considerations
Specific Functional Considerations
Common Injuries
Common Shoulder Injuries
 Joint dislocations
 Clavicular fracture
 Rotator cuff injuries
 Other rotational injuries
 Subscapular neuropathy
Impingement
Possible mechanisms
 Weak or inflexible rotator cuff
 Small anatomical space
 Hyperabduction of GH joint
 GH ABD + ROT
Impingement: Roll-Slide
Kinematics
“Roll” created by
abduction not
countered with
“Slide” action
 During ABD

SSP tendon pushed into
acromion process & CA ligament
 During ROT

SSP tendon dragged along the
inferior surface of the acromion
process
Kinesiological breakdown of overhand throwing
Wind-Up Phase
First Motion
Maximum knee lift of leg
Kinesiological breakdown of overhand throwing
Stride
•Shoulder ABD (DELT & SSP)
•RC maintain proper humeral head position
Lead leg begins to move
Arms separate
Lead foot contacts the ground
Kinesiological breakdown of overhand throwing
Arm
Cocking
• ER in ABD position; ER 150-180°
• ECC action of SUBSCAP (decelerates ER
humerus)
• RC stabilization
Lead foot contact
Maximum shoulder external rotation
Kinesiological breakdown of overhand throwing
Arm
Acceleration
Maximum shoulder ER
• Concentric IR (PMJR & LD )
• IR velocity (> 1000 °/s)
• RC stabilization
Ball release
Kinesiological breakdown of overhand throwing
Arm
Deceleration
Ball release
• Decelerating IR & ADD
• ECC action of TMin
• RC stabilization
Maximum shoulder IR
Kinesiological breakdown of overhand throwing
Follow
Through
Maximum shoulder IR
• Decelerating IR
• ECC action of TMin
• RC stabilization
Ends in balanced position
Rotator Cuff Injuries: Solution
 Alter technique during problem phases
to avoid impingement


Arm cocking
Arm acceleration
 Strengthen rotator cuff
 Surgical repair
Video techniques
Intrinsic Risk Factors
 Age and gender
 Physical fitness
 Overtraining
 Skeletal abnormalities
 Technique
 Warm-up
 Psychological factors
Technique
Technique refers to the movement pattern of an
individual during a particular movement or sequence of
movements. Good technique is a movement pattern
not only effective in performance, but also one that
minimizes risk of injury by appropriately distributing the
overall load throughout the kinetic chain. Poor
technique is characterized by inappropriate utilization
and summation of muscular effort and abnormal joint
movements, both of which result in localized overload
and, therefore, increased risk of injury.
Swimming
Solutions:
Mechanism: ABD + IR
↓ IR
Increase body roll to ↓ ABD
 Lead with hand to

Supraspinatus Tear
Other Rotational Injuries
 Tears of labrum

Mostly in anterior-superior region
 Tears of biceps brachii tendon
 Due to forceful rotational movements

Also: calcification of soft tissues,
degenerative changes in articular surfaces,
bursitis
Biceps Tendon Tear
Subscapular Neuropathy
 Denervation of INF with ↓ strength GH
ER
 Mechanism: Repeated stretching of
nerve
Injury Potential in the
Shoulder Complex - Impacts
Sternoclavicular Joint

not commonly injured
 may sprain anteriorly if fall on
top of shoulder or middle delt pain in horizontal abd
 children may dislocate anteriorly
during throwing because of
increased joint mobility as
compared to adults
 posterior dislocation may occur
when force is applied to sternal
end of clavicle; serious because
of trachea, esophagus, and
blood vessels located
posteriorly
Clavicular Injuries

fx to any part due to direct
trauma
 fx to middle 1/3 can occur by
falling on shoulder, outstretched
arm, or direct trauma to
shoulder that transmits force
down shaft of clavicle
AC Injuries

dislocation from fall on shoulder,
fall on elbow or outstretched
arm
 overuse injuries from overhand
pattern (throwing, tennis,
swimming) or sports that
repeatedly load in the overhead
position (wrestling, wt lifting)
Glenohumeral Injuries
 Most common
dislocation in anterior
(anterior-inferior
95%)
 most commonly
dislocated when
abducted and ER
overhead
 recurrence rate 3350% (66-90% <20
yrs)