Shoulder

Question 1

3 articulations of shoulder girdle

Answer 1

Acromioclavicular joint
Sternoclavicular joint
Scapulothoracic articulation

Question 2

Which articulation of the shoulder girdle is a psuedoarticulation?

Answer 2

Scapulothoracic articulation

Question 3

What are the functions of the scapulothoracic articulation?

Answer 3

Maintain length-tension relationship of rotator cuff/deltoid.
Position glenoid to receive the humeral head.
Absorb shock.
Permit elevation of body, via the scapular depression.
Enhance shoulder range of motion.

Question 4

What are the major movers of the shoulder girdle?

Answer 4

Trapezius (upper, middle, and lower)
Rhomboids
Levator scapulae
Serratus anterior
Pectoralis minor

Question 5

Sternoclavicular articulation characteristics

Answer 5

Diarthrotic and biaxial joint.
Fibrocatilaginous articular disc within the joint capsule.
Improves congruency of articulating surfaces and shock absorbs.

Question 6

Acromioclavicular articulation characteristics

Answer 6

Nonaxial synovial joint - doesn’t move in any cardinal planes, simply glides.
20-30 degrees of total gliding and rotational motion accompanying other shoulder girdle and joint movement.
Supported by acromioclavicular and coraclavicular ligaments.

Question 7

Characteristics of the muscles involved in shoulder girdle movements

Answer 7

All originate on the axial skeleton and insert on the scapula and/or the clavicle.
Don’t attach to the humerus.
Don’t cause should joint actions.
Essential in providing dynamic stability of the scapula - allows it to serve as a relative base for shoulder joint activities.

Question 8

Scaption

Answer 8

Movement of the glenohumeral hoint in the scapular plane, 30-40 degrees anterior to the frontal plane.
Naturally aligns with the angle of the scapula.

Question 9

Characteristics of glenohumeral articulation

Answer 9

Diarthrodial triaxial joint.
Inherently unstable.
Humeral head is twice the size of the glenoid and the labrum deepens the socket.
Grouped into large movers and rotator cuff muscles.

Question 10

Muscles that move the glenohumeral joint originate from…

Answer 10

Scapula
Anterior chest
Sternum and clavicle
Vertebrae

Question 11

Large movers of glenohumeral articulation

Answer 11

Latissimus dorsi
Teres major
Deltoida
Pectoralis major
Coracobrachialis

Question 12

Rotator cuff muscles

Answer 12

Supraspinatus - initiates abduction
Infraspinatus - external rotation
Teres minor - external rotation
Subscapularis - internal rotation

Question 13

Glenohumeral dynamic stabilizers

Answer 13

Superior/middle/inferior glenohumeral ligaments
Coracohumeral ligament
Long head of biceps/triceps
Rotator cuff tendons blend with capsule

Question 14

Humeral flexion and abduction requires scapular…

Answer 14

elevation and rotation upward.

Question 15

Humeral adduction and extension corresponds with scapular…

Answer 15

depression and rotation downward

Question 16

Scapula abduction (protraction) occurs with humeral…

Answer 16

internal rotation and horizontal adduction

Question 17

Scapula adduction (retraction) occurs with humeral…

Answer 17

external rotation and horizontal abduction

Question 18

Force coupling at the shoulder complex

Answer 18

Bones - scapulorhumeral rhythm

Muscularly - upward rotation force coupling

Question 19

Scapulohumeral rhythm

Answer 19

Coupling of shoulder girdle and shoulder joint movement.
When small amount of arm movement is needed glenohumeral joint may act alone.
When a large amount of movement is needed both glenohumeral joint and shoulder girdle must move together.
Occurs in a somewhat predictable pattern - scapular movement generals 1/3 of total shoulder motion.
Each cardinal plane motion of the glenohumeral joint is associated with a specific shoulder girls movement.
Scapular movement begins at 30 degrees of abduction.

Question 20

Upward rotation force coupling

Answer 20

Upper and lower trap coordinate with serratus anterior to create an upward rotation of the scapula.
Some retraction occurs through the middle trap.