MA I: Shoulder Flashcards

1
Q

MA I: Shoulder

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

A

convex, concave

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2
Q

MA I: Shoulder

kinematics of the sternoclavicular joint:

A
  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)
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3
Q

MA I: Shoulder

What type of synovial joint is the acromioclavicular joint?

A

plane joint

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4
Q

MA I: Shoulder

acromioclavicular joint: upward and downward rotation

A

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

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5
Q

MA I: Shoulder

elevation and depression of the scapulothoracic joint

A

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

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6
Q

MA I: Shoulder

kinematics of protraction and retraction

A

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

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7
Q

MA I: Shoulder

  Average “resting” posture of the scapula

A
  • 10° anterior tilt
  • 5-10° upward rotation
  • 35° internal rotation (plane of scapula)
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8
Q

MA I: Shoulder

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

A

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
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9
Q

MA I: Shoulder

what is the angle of retroversion of the humerus

A

30 deg

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10
Q

MA I: Shoulder

Scapulohumeral rhythm

A
  • 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
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11
Q

MA I: Shoulder

elevators of the scapulothoracic joint:

A
  • Upper trapezius
  • Levator scapulae
  • Rhomboid major/minor
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12
Q

MA I: Shoulder

depressors of the scapulothoracic joint

A
  • Lower trapezius
  • Latissimus dorsi
  • Pectoralis minor
  • Subclavius
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13
Q

MA I: Shoulder

protractors of the scapulothoracic joint:

A

serratus anterior

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14
Q

MA I: Shoulder

retractors of the scapulothoracic joint:

A
  • Middle trapezius
  • Lower trapezius
  • Rhomboid minor
  • Rhomboid major
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15
Q

MA I: Shoulder

The prime muscles that abduct the GH joint are the

A

anterior deltoid, middle deltoid, and supraspinatus

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16
Q

MA I: Shoulder

Elevation of the arm through flexion is performed primarily by

A

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

17
Q

MA I: Shoulder

The primary upward rotators of the scapulothoracic joint are

A

serratus anterior and the upper and lower fibers of the trapezius

18
Q

MA I: Shoulder

The primary downward rotators of the scapulothoracic joint are

A

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

19
Q

MA I: Shoulder

Functions of RTC during abduction

A
  • 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.