MA I: Shoulder

Question 1

MA I: Shoulder

The clavicle surface in the sternoclavicular joint is _____ along its longitudinal diameter, and ______ along its transverse diameter

Answer 1

convex, concave

Question 2

MA I: Shoulder

kinematics of the sternoclavicular joint:

Answer 2

1. Elevation 45 deg; depression 10 deg (roll and slide in opposite directions)
2. Protraction up to 30 deg; retraction up to 30 deg (roll and slide in similar directions)
3. Axial rotation up to 35 deg from neutral (spin)

Question 3

MA I: Shoulder

What type of synovial joint is the acromioclavicular joint?

Answer 3

plane joint

Question 4

MA I: Shoulder

acromioclavicular joint: upward and downward rotation

Answer 4

summation of clavicular elevation at the SC joint and scapular upward rotation at the AC joint

Question 5

MA I: Shoulder

elevation and depression of the scapulothoracic joint

Answer 5

elevation at the sternoclavicular joint and downward rotation at the acromioclavicular joint

Question 6

MA I: Shoulder

kinematics of protraction and retraction

Answer 6

protraction at the sternoclavicular joint and slight internal rotation at the acromioclavicular joint

Question 7

MA I: Shoulder

  Average “resting” posture of the scapula

Answer 7

• 10° anterior tilt
• 5-10° upward rotation
• 35° internal rotation (plane of scapula)

Question 8

MA I: Shoulder

at the end range of full shoulder abduction, the position of the scapula is…

Answer 8

posteriorly tilts 20 deg and externally rotates 10 deg

• Clavicle retracts at sternoclavicular joint, which coupled with external rotation of scapula on thorax
• Acromioclavicular joint rotates internally at the same time which offsets a large portion of the scapulothoracic external rotation that occurs from the sternoclavicular joint retraction

Question 9

MA I: Shoulder

what is the angle of retroversion of the humerus

Answer 9

30 deg

Question 10

MA I: Shoulder

Scapulohumeral rhythm

Answer 10

• 120 deg GHJ
• 60 deg STJ:
  
  • 30° elevation SCJ
  • 30° upward rotation at the ACJ
• From 0-90 mostly SCJ
• From 90 to 180 mostly ACJ

Question 11

MA I: Shoulder

elevators of the scapulothoracic joint:

Answer 11

• Upper trapezius
• Levator scapulae
• Rhomboid major/minor

Question 12

MA I: Shoulder

depressors of the scapulothoracic joint

Answer 12

• Lower trapezius
• Latissimus dorsi
• Pectoralis minor
• Subclavius

Question 13

MA I: Shoulder

protractors of the scapulothoracic joint:

Answer 13

serratus anterior

Question 14

MA I: Shoulder

retractors of the scapulothoracic joint:

Answer 14

• Middle trapezius
• Lower trapezius
• Rhomboid minor
• Rhomboid major

Question 15

MA I: Shoulder

The prime muscles that abduct the GH joint are the

Answer 15

anterior deltoid, middle deltoid, and supraspinatus

Question 16

MA I: Shoulder

Elevation of the arm through flexion is performed primarily by

Answer 16

anterior deltoid, coracobrachialis, and long head of the biceps brachii

Question 17

MA I: Shoulder

The primary upward rotators of the scapulothoracic joint are

Answer 17

serratus anterior and the upper and lower fibers of the trapezius

Question 18

MA I: Shoulder

The primary downward rotators of the scapulothoracic joint are

Answer 18

latissimus dorsi, levator scapulae, pectoralis minor/major, rhomboids

Question 19

MA I: Shoulder

Functions of RTC during abduction

Answer 19

• Supraspinatus compresses humeral head into glenoid
• Subscapularis, infraspinatus, teres minor inferior glide of the humeral head
•  Infraspinatus, teres minor rotates humeral head externally to increase the clearance between the greater tubercle and the acromion.