Kinesiology - Module 6

The scapula articulates to keep these two things together

Glenoid fossa and humeral head

The scapula rests on these two muscles

Serratus anterior and subscapularis

Only osseous connection between the axial skeleton and the upper extremity

Sternoclavicular joint

What type of joint is the sternoclavicular joint?

Modified ball and socket joint

What type of joint is the acromioclavicular joint?

Synovial joint - gliding

Link between the clavicle and scapula

Acromioclavicular joint

What are the two ligaments at the acromioclavicular joint?

Acromioclavicular (AC) and coracoclavicular (CC)

What are the two functions of the acromioclavicular joint?

To transmit loads on upper extremity to axial skeleton via clavicle and to allow scapular movements to accommodate shape of thoracic wall during arm motion

Which shoulder muscles facilitate scapular retraction?

Lower trapezius and rhomboids

Which shoulder muscles facilitate scapular protraction?

Serratus anterior and pectoralis minor

Which shoulder muscles facilitate scapular elevation?

trapezius (upper and middle fibers), levator scapulae, rhomboids (both)

Which shoulder muscles facilitate scapular depression?

Lower trapezius, subclavius, pectoralis minor

Which shoulder muscles facilitate scapular upward rotation?

Serratus anterior, trapezius (all fibers)

Which shoulder muscles facilitate scapular downward rotation?

Pectoralis minor, levator scapulae, rhomboids

The true shoulder joint

Glenohumeral (GH) joint

Most mobile joint in the body

Glenohumeral joint

The shoulder joint sacrifices ______________ for ______________

Stability for mobility

List the 4 rotator cuff muscles

supraspinatus, infraspinatus, teres minor, subscapularis

Which rotator cuff muscle is anterior?

subscapularis

What are the 8 motions are the glenohumeral joint?

Flexion/extension, abduction/adduction, internal/external rotation, horizontal abduction/adduction

What are the classifications for the glenohumeral joint?

ball and socket ; Triaxial diarthrotic

What are the static stabilizing structures of the glenohumeral joint?

Capsulo-ligamentoux complex (CLC), bony geometry, glenoid labrum

What is the dynamic stabilizing structure of the glenohumeral joint?

Musculo-tendinous influences

What are the 2 mechanisms of the glenohumeral joint for providing stability?

Glenoid fossa and humeral head contact area, articular surface congruency

Effect of the fibrous rim deepening the glenoid fossa, increasing total surface contact area between the glenoid and humeral head

Buttress effect

Primary dynamic stabilizers of the glenohumeral joint

Rotator cuff (supraspinatus, infraspinatus, teres minor, subscapularis)

Secondary dynamic stabilizers of the glenohumeral joint

Teres major, latissimus dorsi, pectoralis major, long head of biceps, deltoid

What muscles facilitate flexion at the glenohumeral joint?

Pectoralis major (clavicular), anterior deltoid, coracobrachialis, biceps brachii

What muscles facilitate extension at the glenohumeral joint?

Posterior deltoid, latissimus dorsi, teres major, triceps brachii (long head only)

What is the primary mover of the glenohumeral extensors and adductors?

Gravity

These two glenohumeral extensors do everything together

Latissimus dorsi and teres major

What muscles facilitate abduction at the glenohumeral joint?

deltoid (anterior, posterior, and medial), supraspinatus

What muscles facilitate adduction at the glenohumeral joint?

latissimus dorsi, teres major, pectoralis major (sternal), coracobrachialis, triceps brachii

What muscles facilitate internal rotation at the glenohumeral joint?

Pectoralis major (all fibers), anterior deltoid, latissimus dorsi, teres major, subscapularis

What muscles facilitate external rotation at the glenohumeral joint?

infraspinatus, teres minor, posterior deltoid (small assistance)

What muscles facilitate horizontal abduction rotation at the glenohumeral joint?

deltoid (posterior and medial), infraspinatus, teres minor

What muscles facilitate horizontal adduction rotation at the glenohumeral joint?

pectoralis major (all fibers), anterior deltoid, coracobrachialis

List the strengths of the shoulder complex from strongest to weakest

Adduction, extension, flexion, abduction, internal rotation, external rotation

Where is the shoulder in the safest position?

Slightly externally rotated

Because the ___________ and _____________ are connected through the joints of the shoulder, they must move together.

Scapula and humerus

For full shoulder abduction/flexion ROM (about 180 degrees), GH motion contributes about ________ degrees

120

For full shoulder abduction/flexion ROM (about 180 degrees), scapular motion contributes about ________ degrees

60

Ratio of humeral to scapular motion during flexion and abduction

Scapulohumeral rhythm

From ____ to _____ degrees of shoulder abduction/flexion, there is no scapular motion

0 to 30

From ____ to _____ degrees of shoulder abduction/flexion, there is one degree of scapular upward rotation for every 2 degrees of humeral elevation

30 to 90

From ____ to _____ degrees of shoulder abduction/flexion, there is 1 degree of scapula upward rotation and abduction for every 1 degree of humeral elevation

90 to 180

What is a common cause of shoulder injuries?

Falling on an outstretched arm

This shoulder injury is described as a tear/severe separating of AC ligaments

AC separation (separated shoulder)

Most common shoulder fracture

Clavicular (middle third)

Why are fractures so common in the middle third of the clavicle?

Because that is where the shape of the bone changes, it dips a bit

Capsule surrounding shoulder contracts and scars preventing movement

Frozen shoulder (adhesive capsulitis)

When a person is not conscious their shoulder works fine passively

Idiopathic etiology

Tear in the fibrocartilage surrounding the joint

Labrum tear

Adolescent fracture of the clavicle is known as ______________

Greenstick

Shoulder instability from acute trauma or chronic overuse

Luxation/subluxation

Most dangerous shoulder position for the rotator cuff

Overhead position

Impingement at the shoulder happens between the ____________ and ___________

Humerus and acromion

This genetic factor can determine the risk for rotator cuff injuries

Acromion morphology

Which is the worst acromion morphology?

Type 3

Shoulder injury where Supraspinatus tendon is inflamed and impinged

Impingement syndrome (swimmers shoulder)

Elbow and anterior shoulder injuries happen during this phase of overhead movements

Acceleration

Posterior shoulder injuries happen during this phase of overhead movements

Deceleration