Movement Analysis Wk 2: Shoulder

The shoulder provides gross positioning and stability, but it is also a functional connection between what two structures?

Trunk and upper extremity (proximal stability + distal mobility)

What are the 3 bones of the shoulder complex?

Scapula

Humerus

Clavicle

Shoulder girdle

Attachment for numerous muscles

Positions glenoid fossa for humeral motion

Scapula

Links chest and upper arm

Positions humerus laterally away from upper body

Clavicle

Connects the trunk and forearm

Humerus

What are the 4 shoulder complex JOINTS?

1. Scapulothoracic joint

2. Sternoclavicular joint

3. Acromioclavicular joint

4. Glenohumeral joint

Saddle or ball-and-socket joint

Triaxial

Formed by the medial clavicle and the sternum

Movements:

Elevation

Depression

Protraction

Retraction

Posterior rotation*

Anterior rotation*

Sternoclavicular joint

This is the only joint that the shoulder complex articulates with the axial skeleton

Sternoclavicular joint (SC)

Important for gliding

Biaxial

Movements:

Anterior/posterior gliding

Superior/inferior gliding

Acromioclavicular joint (AC)

This joint maintains the relationship between the clavicle and the scapula

Acromioclavicular joint

Contributes to scapulothoracic movements: anterior and posterior tipping, upward rotation and downward rotation

Acromioclavicular joint

Shoulder separation occurs here

AC joint

Shrugging shoulders is what?

Scapular elevation

Raising arm overhead is what?

Shoulder elevation (shoulder flexion)

Ball-and-socket

Triaxial

Movements:

Flexion

Extension

Abduction/adduction

Internal rotation

External rotation

Horizontal abduction/adduction

Glenohumeral (shoulder) joint

Not a true articulation, but its movement is essential for normal function of the upper extremity

Movements:

• Gliding (elevation, depression, abduction, adduction)

• Rotation (internal, external, upward, downward)

• Tilt (anterior, posterior)

Scapulothoracic joint

Roughly the first 10 to 30 degrees of shoulder flexion occurs mostly at what joint?

Glenohumeral joint

The scapula and humerus move in what ratio?

1:2

The combination of glenohumeral motion accompanied by scapular upward rotation is referred to as what?

Scapulohumeral Rhythm

What are the 5 axioscapular muscles?

1. Trapezius

2. Levator scapulae

3. Rhomboids

4. Serratus anterior

5. Pectoralis minor

Stabilizes and mobilizes scapula

Positioning of proximal upper extremity

Functionally is 3 muscles

Trapezius

Elevation and downward rotation of scapula

Levator scapulae

Elevation and downward rotation of scapula

Adduction of scapula

Rhomboids

Maintains position of scapula against rib cage

Serratus Anterior

Damage to thoracic nerve

Scapular winging

Stabilizes scapula anteriorly against rib cage

Pectoralis Minor

What are the scapulohumeral muscles (3)?

Rotator cuff

Deltoid

Teres major

These muscles are active when reaching, placing, or throwing

Scapulohumeral

What are the 4 rotator cuff muscles?

Infraspinatus

Teres minor

Subscapularis

Suprascapularis

Function as a force couple to control the head of the humerus in the glenoid fossa / maintain functional integrity of the GH joint

Rotator cuff

What are the primary movers of shoulder flexion (3)

What is the plane and axis?

1. Deltoid (anterior)

2. Pectoralis Major

3. Biceps brachii

Sagittal plane around a frontal axis

The deltoid controls what three movements?

Flexion

Abduction

Extension

This muscle controls adduction and internal rotation

Teres major

What two muscles control shoulder abduction?

Ex. Holding a hose to water a garden

Plane and axis?

Deltoid (all) and supraspinatus

Frontal plane around a saggital axis

Many ADLs require what motion?

Shoulder elevation

Weakness of serratus anterior

Impairs scapular mobility

Interrupts functional movement of shoulder

Scapular winging

Result of instability, weakness, or paralysis

Pull of gravity through humerus

Painful strain of joint capsule

Subluxation

Beyond 30 degrees flexion, the scapula and humerus move at what ratio?

1: 2

Why is it essential to maintain upright posture of the trunk and scapula (2)?

To maintain balance

Promote purposeful movement of the shoulder

Compression of the soft tissues between acromion and humeral head

Subacromial impingement

Injury usually due to forceful loading of shoulder while elevated

What muscle is most commonly injured?

Rotator Cuff Tear

Supraspinatus

When a person has a CVA or any condition that causes paralysis, the head of the humerus drops inferiorly on the glenoid fossa. The joint surfaces are still partially in contact but not completely

Glenohumeral subluxation

Most commonly dislocated joint in the body

Involves damage to the labrum

Leads to instability

Glenohumeral joint dislocation

The joint surfaces (head of humerus and glenoid fossa) are no longer in contact with each other

Dislocation

Can significantly limit function (ROM)

Requires activity modification or adaptive equipment

No cure (cortisone injections)

Osteoarthritis