Myology of the Shoulder girdle

Question 1

Upper trapezius

Answer 1

• Origin: Occipital bone: superior nuchal line and external
  protuberence, nuchal lig., spinous process C7.
• Insertion: Lateral third of clavicle.
• Action: Elevation of the scapula; Ipsi inclination (unilateral)
  extension of the head (bilateral).
• Innervation: Accessory nerve (cervical plexus).

Question 2

Intermediate trapezius

Answer 2

• Origin: Spinous process T1-T4.
• Insertion: Acromion.
• Action: Retraction of the scapula.
• Innervation: Accessory nerve (cervical plexus).

Question 3

Lower trapezius

Answer 3

• Origin: Spinous process T5-T12.
• Insertion: Spine of scapula.
• Action: Scapula: Retraction, depression, upward rot.
• Innervation: Accessory nerve (cervical plexus).

Question 4

Rhomboids major and minor

Answer 4

• Origin Major: Spinous process T2-T5.
  Origin Minor: Spinous process C7-T1.
• Insertion: Medial margin of the scapula.
• Action: Scapula- Retraction, elevation, downward rotation.
• Innervation: Dorsal scapular nerve (cervical plexus).

Question 5

Levatore scapulae

Answer 5

• Origin: Transverse process C1-C4.
• Insertion: Superior angle of the scapula.
• Action: Proximal insertion fixed: elevation, downward
  rotation of the scapula. Distal insertion fixed : extension and
  ipsilateral. Inclination of cervical spine.
• Innervation: Dorsal scapular nerve (cervical plexus).

Question 6

Serratus anterior

Answer 6

• Origin: 1st-9th rib.
• Insertion: Medial margin of the scapula.
• Action: Protraction and upward rotation of scapula.
• Innervation: Long thoracic nerve.

Question 7

Subclavius

Answer 7

• Origin: 1st rib.
• Insertion: Lateral third of inferior face of clavicle.
• Action: Depression of scapula, coaptation of
  sternoclavicular joint.
• Innervation: Subclavius nerve.

Question 8

Pectoralis minor

Answer 8

• Origin: 3th-5th ribs.
• Insertion: Coracoid process.
• Action: Distal insertion fixed : scapula depression,
  protraction, and downward rotation. Proximal insertion fixed:
  elevation of ribs à accessory inspiration.
• Innervation: Medial pectoral nerve.

Question 9

Supraspinatus

Answer 9

• Origin: Supraspinous fossa.
• Insertion: Major tubercle of the humerus.
• Action: Shoulder: Abduction, synergic action with external
  rotator muscles.
• Innervation: Suprascapular nerve.

Question 10

Infraspinatus

Answer 10

• Origin: Infraspinous fossa.
• Insertion: Major tubercle of the humerus.
• Action: Shoulder: external rotation.
• Innervation: Suprascapular nerve.

Question 11

Teres minor

Answer 11

• Origin: 2/3 sup of lateral margin of the scapula.
• Insertion: Major tubercle of the humerus.
• Action: Shoulder: External rot., Adduction.
• Innervation: Axillary nerve.

Question 12

Subscapularis

Answer 12

• Origin: Subscapular fossa.
• Insertion: Minor tubercle of the humerus.
• Action: Shoulder Internal rotation.
• Innervation: Subscapular nerve.

Question 13

Muscles of the rotator cuff

Answer 13

Avoid separation of the humeral head from the glenoid cavity).
Subscapularis - only one superior to scapula, not inserting in greater tubercle.
Supraspinatus - Superior, passes under acromion.
Infraspinatus - Primary external rotator
Teres minor - Primary external rotator (synergist with infrasp.)

Question 14

Teres major

Answer 14

• Origin: Inferior angle of the scapula.
• Insertion: Medial side of the bicipital groove.
• Action: Adduction, extension, internal rotation of the
  shoulder.
• Innervation: Subscapular nerve.

Question 15

Deltoid anterior (clavicular) fibers

Answer 15

• Origin: Lateral third of clavicle.
• Insertion: Deltoid tuberosity.
• Action: Shoulder: flexion, abduction, internal rotation,
  horizontal ADD.
• Innervation: Axillary nerve.

Question 16

Deltoid middle (acromial) fibers

Answer 16

• Origin: Acromion.
• Insertion: Deltoid tuberosity.
• Action: Shoulder: Abduction.
• Innervation: Axillary nerve.

Question 17

Deltoid posterior (spinal) fibers

Answer 17

• Origin: Spine of the scapula.
• Insertion: Deltoid tuberosity.
• Action: Shoulder: extension, external rot., horizontal
  abduction.
• Innervation: Axillary nerve.

Question 18

Latissimus dorsi

Answer 18

• Origin: Spinous process T7-S5 (via thoracolumbar fascia),
  iliac crest, 9-12th ribs, inferior angle of the scapula.
• Insertion: Medial side of bicipital groove.
• Action: Shoulder extension, adduction, internal rot.
• Innervation: Thoracodorsal nerve.

Question 19

Coracobrachialis

Answer 19

• Origin: Coracoid process.
• Insertion: Middle third of medial margin of the humerus.
• Action: Shoulder: flexion, adduction.
• Innervation: Musculocutaneus nerve.

Question 20

Pectoralis major

Answer 20

• Origin: Clavicular fibers: Medial half of the clavicle
  Sternocostal fibers: Sternum, 2nd-6th costal cartilages.
• Insertion: Lateral margin of the bicipital groove.
• Action: Shoulder adduction, horiz. adduction, internal rot.
  (entire muscle); flexion (clavicular fibers).
• Innervation: Medial and lateral pectoral nerve.

Question 21

Muscles of the glenohumeral joint

Answer 21

Supraspinatus
Infraspinatus
Teres minor 
Subscapularis
Teres major
Deltoid
Latissimus dorsi
Coracobrachialis 
Pectoralis major
Bicep brachii
Tricep brachii

Question 22

Muscles of the shoulder girdle

Answer 22

Trapezius
Rhomboids
Levatore scapulae
Serratus anterior
Subclavius
Pectoralis minor

Question 23

Main shoulder adductors?

Answer 23

Teres major
Latissimus dorsi
synergists

Question 24

Most important shoulder muscle regarding movement?

Answer 24

Deltoid

Does everything except adduction.

Question 25

Bi-articular muscles

Answer 25

Biceps brachii
Triceps brachii
Move both shoulder and elbow articulations.
Very good stabilizers.