KIN 307 Quiz 2

How does the shoulder girdle attach to the axial skeleton?

How does the shoulder girdle attach to the axial skeleton?

via the clavicle at the sternoclavicular joint

How does a more mobile joint perform in stabilizing?

the less stable it is

How does a less mobile joint perform in stabilizing?

the more stable it is

What is the scapulas only bony link to the axial skeleton?

the clavicle

What bones serve as attachment points for shoulder muscles?

clavicle, humerus, and scapula

Where do shoulder girdle muscles originate?

axial skeleton

Where do shoulder girdle muscles insert?

clavicle or scapula

Muscles confined to shoulder girdle movements do not attach to humerus and do not cause glenohumeral (shoulder) joint actions

true

The shoulder girdle is essential in providing ------- of the scapula so it can serve as a relative base of support for shoulder joint activities

dynamic stability

Muscles primarily involved in shoulder girdle movements

1. Trapezius

2. Rhomboids

3. Levator scapulae

4. Serratus anterior

5. Pectoralis minor

6. Subclavius

The shoulder girdle is considered \n an ---- mechanical system

open

What are advantages of the right and left sides of the shoulder girdle not being attached?

independent movement leading to greater ROM and less stability

What is the physiological articulation between the scapula and the thoracic wall?

none, sits on serratus anterior and subscapularis (no bone to bone contact)

How is scapular movement associated?

with movement at Sternoclavicular and/or Acromioclavicular joints

Where is the only osseous connection between the axial skeleton and the upper extremity of the shoulder girdle?

Sternoclavicular joint

Which joint of the shoulder girdle has a great deal of ligament attachment?

Sternoclavicular joint

Which joint of the shoulder girdle is a modified ball and socket joint?

Sternoclavicular joint

What type of joint is the Acromioclavicular joint?

Synovial joint – gliding

Which joint is the link between the clavicle and scapula?

Acromioclavicular joint

Which joint has the function of transmitting loads on upper extremity to axial skeleton through the clavicle?

Acromioclavicular joint

Ligaments of the shoulder girdle?

Acromioclavicular, Coracoacromial, Coracoclavicular (Conoid, Trapezoid)

Why is the scapula shaped the way that it is?

Allows scapular movements to accommodate shape of thoracic wall during arm motion

What is the scapulothoracic motion?

to provide synergy with muscles of glenohumeral joint

Why does the scapula move for the humerus?

So that the glenoid fossa is in the correct position for movement

What happens without the accompanying scapular movement of the humerus?

the humerus can only be raised into approximately 90° of total shoulder abduction and flexion

Are the GH joint and shoulder girdle synergists?

Yes

scapular elevation muscles

Trapezius (upper & middle fibers), Levator Scapulae, Rhomboids (both)

scapular depression muscles

Trapezius (lower fibers), Pectoralis Minor, Subclavius

scapular protraction muscles

Serratus Anterior, Pectoralis Minor

scapular retraction muscles

Trapezius (lower fibers), Rhomboids (both)

scapular upward rotation muscles

Serratus Anterior, Trapezius (all fibers)

scapular downward rotation muscles

Pectoralis Minor, Levator Scapulae, Rhomboids (both)

Static stabilizing structures of GH joint

Capsulo-ligamentous complex (CLC), Bony geometry, Glenoid labrum

Dynamic stabilizing structures of GH joint

Musculo-tendinous influences (especially rotator cuff)

Capsulo-ligamentous complex (CLC)

Coracohumeral – coracoid to greater tubercle

3 GH bands – thickenings of articular capsule

1.Superior GH Ligament

2.Middle GH Ligament

3.Inferior GH Ligament Complex (IGHLC)

Bony geometry for GH joint:

1. Glenoid fossa and humeral head contact area. 25 – 30% of humeral head contacts glenoid fossa.

2. Articular surface congruency. Glenoid fossa orientation and Humeral head orientation

What does the body geometry sacrifice for great mobility?

stability

How much does the Genoid Labrum increase joint depth?

50%

What creates the buttress effect and increases the surface area for GH articulation?

Glenoid Labrum

Primary dynamic Stabilizers of GH joint?

rotary cuff: SITS

Secondary dynamic Stabilizers of GH joint?

Teres Major, Latissimus Dorsi, Pectoralis Major, Long Head of Biceps*, Deltoid

What must the rotator cuff muscles possess?

muscular strength and endurance

How do rotator cuff muscle injuries occur?

when conducting repetitious overhead activities

What injuries can a rotator cuff sustain?

tendinitis and rotator cuff impingement within sub-acromial space

Glenohumeral Joint muscles

Pectoralis major, Deltoid, Coracobrachialis, Teres major, Latissimus dorsi, Rotator cuff musculature (SItS)

Five degrees of freedom of GH joint:

Flexion/Extension, Abduction/Adduction, Internal/External Rotation, Horizontal Abduction/Adduction, Diagonal Abduction/Adduction

Should the scapula and humerus move together?

Yes

The scapula must help to ---- the shoulder in order for full ROM for the GH joint to be reached

clear

Ratio of humeral to scapular motion during abduction referred to as:

scapulohumeral rhythm

What is the ration of motion between the scapula and the humerus?

2:1 ratio (2° of humeral motion for every 1° of scapular motion).

For full shoulder abduction/flexion ROM:

≈180°

No scapular motion:

0° to 30°

1° scapular upward rotation for every 2° humeral elevation:

30° to 90°

1° scapula upward rotation and protraction for every 1° humeral elevation:

90° to 180°

Shoulder flexion:

movement of humerus straight anteriorly.

Shoulder extension:

movement of humerus straight posteriorly.

Shoulder abduction:

upward lateral movement of humerus out to the side, away from body

Shoulder adduction:

downward movement of humerus medially toward body from abduction

external rotation:

movement of humerus laterally around its long axis away from midline

internal rotation:

movement of humerus medially around its long axis toward midline

horizontal adduction:

movement of humerus in a horizontal or transverse plane toward and across chest

horizontal abduction:

movement of humerus in a horizontal or transverse plane away from chest

diagonal abduction:

movement of humerus in a diagonal plane away from midline of body

diagonal adduction:

movement of humerus in a diagonal plane toward midline of body

shoulder joint: abduction

shoulder girdle: upward rotation

shoulder joint: adduction

shoulder girdle: downward rotation

shoulder joint: flexion

shoulder girdle: elevation/upward rotation

shoulder joint: extension

shoulder girdle: depression/downward rotation

shoulder joint: internal rotation

shoulder girdle: protraction

shoulder joint: external rotation

shoulder girdle: retraction

shoulder joint: horizontal abduction

shoulder girdle: retraction

shoulder joint: horizontal adduction

shoulder girdle: protraction

Glenohumeral flexion:

Pectoralis major (upper fibers), Deltoid (anterior fibers), Coracobrachialis, biceps brachii

Glenohumeral extension:

Deltoid (posterior fibers), Latissimus Dorsi, Teres major, Triceps brachii (long head only)

Glenohumeral adduction:

Pectoralis Major (lower fibers), Latissimus Dorsi, Teres major, Coracobrachialis, Triceps brachii

Glenohumeral abduction:

Deltoid (posterior and medial fibers), Supraspinatus

Glenohumeral internal rotation:

Pectoralis Major (all fibers), Latissimus Dorsi, Teres major, Deltoid (anterior fibers), subscapularis

Glenohumeral external rotation:

Infraspinatus, Teres Minor, Deltoid (posterior fibers; small assistance)

Glenohumeral horizontal adduction:

Pectoralis Major (all fibers), Deltoid (anterior fibers), coracobrachialis

Glenohumeral horizontal abduction:

Infraspinatus, teres minor, Deltoid (posterior and medial fibers)