SCAPULAR MUSCLES CONTRIBUTING TO

ELEVATION

1. Levator Scapula
2. Rhomboid Major and Minor
3. Serratus Anterior
4. Pectoralis Minor
5. Subclavius
6. Trapezius

Muscles form a rigid base to stabilize the shoulder

eg Holding a suitcase-- Levator scap, trap, rhomboids, & supraspinatus stabilize shoulder against added weight

Position the Glenohumeral joint correctly for motion

GLENOHUMERAL MUSCLE CONTRIBUTIONs TO

ELEVATION

• Deltoid
• Pectoralis Major
• Lattisimus Dorsi
• Coracobrachialis
• Teres Major
• Biceps
• Triceps
• Rotator Cuff:
  • Supraspinatus
  • Infraspinatus
  • Teres Minor
  • Subscapularis

SUPRASPINATUS

INFRASPINATUS

TERES MINOR

SUBSCAPULARIS

1. Cause some ROTATION of HUMERUS

2. Compress the head of Humerus INTO the glenoid fossa

3. (Supraspinatus) Initiate ABDuction until middle deltoid takes over

STABILITY                                                  MOBILITY

-Prevent dislocation                                      -Produce shoulder motions

What muscle initiates ABDuction?

ADDuction?

ABDuction= Suprapinatus

ADDuction= Lattisimus Dorsi

Muscles located on anterior of joint:

Anterior Deltoid

Clavicular Head of Pectoralis Major

Located on Posterior Aspect:

1. Sternal head of Pectoralis Major
2. Teres Major
3. Latissimus Dorsi

Muscles located on superior GH joint aspect:

1. Middle Deltoid (90-180)
2. Supraspinatus (Initiates, 0-110 degrees)

Located on inferior aspect:

1. Latissimus Dorsi
2. Teres Major
3. Sternal head of Pectoralis Major

Inward or medial rotation

Located anteriorly

1. Subscapularis
2. Teres Major

Often occurs with supination

Outward or Lateral Rotation

Located posteriorly

1. Infraspinatus
2. Teres Minor

Occurs with supination when elbow extended

1. middle deltoid
2. posterior deltoid
3. infraspinatus
4. teres minor

(Teres Major and Lats ASSIST)

HORIZONTAL ADDuction OF GH

1. Pectoralis major (BOTH heads)
2. Anterior Deltoid
3. Corocobrachialis

Why is SUPERIOR dislocation unlikely?

1. Support from corocoacromial (superhumeral) arch
2. Corocohumeral ligament
3. Abductors that cross superiorly (Middle Deltoid & Supraspinatus)

1. Stability is sacrificed for MOBILITY
   
2. Glenoid fossa is a bad fit
   
3. Loose-packed when in neutral

Role of Labrum

Components

1. Add STABILITY
   
2. Increase articular surface of GH joint

• Ring of fibrocartilage on periphery of fossa
• Purposes: Spread load, improve fit, limit slip, protect periphery, lubricate, absorb shock

1. Elevation/Depression
2. Upward/Downward Rotation
3. Abduction/Adduction
4. Winging
5. Tipping

1. Elevation & Depression of LATERAL end of Clavicle
2. Protraction/Retraction
3. Rotation of entire clavicle
   •  
     • Occurs w/ Flexion & ABD
     • ONLY occurs in posterior direction
     • Ex: shrugging shoulders, arms over head

Sternoclavicular Joint

Movement of scap produces mvt at clavicle and vice versa

TRI-AXIAL

Plane/gliding joint

1. Scapular Rotation- Upward/Downward (Occurs w/ UE elevation)
2. Protraction/Retraction
3. Elevation/Depression
4. Winging
5. Tipping

• Maintain contact btw scap and clav during early elevation
• Allow scap additional ROM later in elevation

Primary motion of scapula at AC joint is ___________

____ Plane

____ Axis

SCAPULAR ROTATION (upward/downward)

Frontal Plane

Anteroposterior Axis

** AC movement SYNONYMOUS w ST mvt

Winging of AC Joint

Occurs along ___ Axis

• Normal POSTERIOR mvt of Vertebral border
• Occurs along Longitudinal Axis
• Occurs along with PROTRACTION
• Function: KEEP SCAPULA FLAT AGAINST RIB CAGE DURING SCAP ABD/ADD (Pro/Ret)
• Result: Glenoid Fossa facing anteriorly w/ scapula in contact w/ rib cage (Creates better fit)

Inferior angle tips ourward (posteriorly) as scapula moves into elevation & depression

Function: Maintain contact of scapula with rib cage

• Elevation/Depression
• Up/Downward Rotation
• Ab/Adduction
• Winging
• Tipping

Suprahumeral "Joint"

AKA ______

AKA Corocoacromial arch

Joint forms osteoligamentous vault that protects humeral head from SUPERIOR disolcation

• When arm is at rest at side of body
• Bony surfaces alone are not a strong enough articulation to maintain contact due to pull of gravity
• SUPRASPINATUS gives passive tension to maintain contact
• Upward force is applied by superior joint capsule and corocohumeral ligaments (taunt when UE at rest)

Coordinated mvt achieved through ST and GH mvt

2:1 degree movement GH:Scap

During inital stages of elevation, motion PRIMARILY occurs at GH

 (Adding stress makes scap move earlier)

Purpose of ST Joint Scapulohumeral rhythm

• Distribute motion btw joints resulting in > ROM without compromising stability
• Maintain glenoid fossa in OPTIMAL position to receive the head of humerus
• Permits muscles acting on humerus to MAINTAIN good length so TENSION IS OPTIMAL

Elevation at SC Joint

During first 90 of humeral elevation, clavicle ______ _______ at the same time

Elevation at AC joint

Rotation at AC Joint occurs with _____ _____ of ______ elevation and again as UE moved from _____ to ____

Rotation at AC joint occurs with first 30 degrees of humeral elevation and again as UE moved from 135 to 180 degrees.

Rotation occurs along LONGITUDINAL axis of joint

Stability

Prevent dislocation

Mobility

Produce shoulder motions