Muscles Of The Thorax And Shoulder That Move The Humerus

Question 1

Pectoralis major

Axial muscle

Answer 1

O- Medial half of clavicle, sternum and cartilage a first through sixth ribs

I-Crest of greater tubercle of humerous

A-All fibers:
Adduct The shoulder [glenohumeral joint]
Mediately rotate the shoulder [g/h joint]
Assist to elevate the thorax during forced inhalation. [With the arm fixed]
Upper fibers: Flex the shoulder [G/H joint]
Horizontally adduct the shoulder [G/H joint]
Lower fibers: extend the shoulder [G/H joint]

N-Upper fibers: lateral pectoral C-5, 6, 7
Lower fibers: lateral and medial pectoral C6, 7, 8, T1

Question 2

Latissimus dorsi

Axial muscle

Answer 2

O-Inferior angle of scapula, spinous processes of last 6 thoracic vertebrae, last three or four ribs, thoracolumbar aponeurosis and posterior iliac crest

I-Intertubercular groove of the humerus

A-Extend the shoulder [glenohumeral joint]
Adduct the shoulder [G/H joint]
Mediately rotate the shoulder [G/H joint]

N-thoracodorsal C6, 7, 8

Question 3

Deltoid

Scapular muscle

Answer 3

O-Lateral 1/3 of clavicle, acromion

I-deltoid tuberosity

A-All fibers: Abduct the shoulder [glenohumeral joint]
Anterior fibers: Flex the shoulder [G/H joint]
Medially rotate the shoulder [G/H joint]
Horizontally adduct the shoulder [G/H joint]
Posterior fibers: Extend the shoulder [G/H joint]
Laterally rotate the shoulder [G/H joint]
Horizontally abduct the shoulder [G/H joint]

N-Auxiliary C5, 6

Question 4

Subscapularis

Scapular muscle

Answer 4

O-Scapular fossa of the scapula

I-Lesser tubercle of humerus

A-Medially rotate the shoulder [G/H joint]
Stabilize the head of humerus in glenoid cavity

N-Upper and lower subscapular by C5, 6, 7

Question 5

Supraspinatus

Scapular muscle

Answer 5

O-Supraspinous fossa of the scapula

I- Greater tubercle of the humerus

A-Abduct the shoulder [G/H joint]
Stabilize the head of humerus in glenoid cavity

N-Suprascapular C4, 5, 6

Question 6

Infraspinatus

Scapular muscle

Answer 6

O-Infraspinous fossa of the scapula

I-Greater tubercle of humerus

A-Literally rotate the shoulder [G/H joint]
Adduct the shoulder [G/H joint]
Stabilize the head of humerus in glenoid cavity

N-Suprascapular C4, 5, 6

Question 7

Teres major

Scapular muscle

Answer 7

O-Inferior angle and lower 1/3 of lateral border of scapula

I-Crest of the lesser tubercle of humerus

A-Extend the shoulder [G/H giant]
Adduct the shoulder [G/H joint]
Mediately rotate the shoulder [G/H joint]

N-Lower subscapular C5, 6, 7

Question 8

Teres minor

Scapular muscle

Answer 8

O-Upper 2/3 of lateral border of the scapula

I-Greater tubercle of humerus

A-Laterally rotate the shoulder [G/H joint]
Adduct the shoulder [G/H joint]
Stabilize the head of the humerus in glenoid cavity

N-Auxiliary C5, 6

Question 9

Coracobrachialis

Scapular muscle

Answer 9

O-Coracoid process of the scapula

I-Medial surface of mid-humeral shaft

A-Flex the shoulder [G/H joint]
Adduct the shoulder [G/H joint]

N-Musculocutaneous C6, 7