Thorax Muscles

Question 1

Pectoralis Major- Clavicular Head Origin

Answer 1

Anterior surface of medial half of clavicle

Question 2

Pectoralis Major- Clavicular Head Insertion

Answer 2

Lateral lip intertubercular sulcus of humerus

Question 3

Pectoralis Major- Clavicular Head Innervation

Answer 3

Lateral and medial pectoral nerves; clavicular head (C5,C6), sternocostal head (C7,C8,T1)

Question 4

Pectoralis Major- Clavicular Head Action

Answer 4

Both heads adducts and medially rotates humerus; draws scapula anteriorly and inferiorly. Clavicular head flexes humerus

Question 5

Pectoralis Major- Sternocostal Head Origin

Answer 5

Anterior surface of sternum, superior six costal cartilages, aponeurosis of external oblique muscle

Question 6

Pectoralis Major- Sternocostal Head Insertion

Answer 6

Lateral lip intertubercular sulcus of humerus

Question 7

Pectoralis Major- Sternocostal Head Innervation

Answer 7

Lateral and medial pectoral nerves; clavicular head (C5,C6), sternocostal head (C7,C8,T1)

Question 8

Pectoralis Major- Sternocostal Head Action

Answer 8

Both heads adducts and medially rotates humerus; draws scapula anteriorly and inferiorly. Sternocostal head extends it from the flexed position

Question 9

External Intercostal Origin

Answer 9

Inferior border of ribs

Question 10

External Intercostal Insertion

Answer 10

Superior border of ribs below

Question 11

External Intercostal Innervation

Answer 11

Intercostal nerve

Question 12

External Intercostal Action

Answer 12

Elevate ribs during forced inspiration

Question 13

Internal Intercostal & Innermost Intercostal Origin

Answer 13

Inferior border of ribs

Question 14

Internal Intercostal & Innermost Intercostal Insertion

Answer 14

Superior border of ribs below

Question 15

Internal Intercostal & Innermost Intercostal Innervation

Answer 15

Intercostal nerve

Question 16

Internal Intercostal & Innermost Intercostal Action

Answer 16

Interosseous part: depresses ribs

Question 17

Transversus Thoracis Origin

Answer 17

Posterior surface of lower sternum

Question 18

Transversus Thoracis Insertion

Answer 18

Internal surface of costal cartilages 2-6

Question 19

Transversus Thoracis Innervation

Answer 19

Intercostal nerve

Question 20

Transversus Thoracis Action

Answer 20

Weakly depress ribs and proprioception

Question 21

Subcostal Origin

Answer 21

Internal surface of lower ribs near their angles

Question 22

Subcostal Insertion

Answer 22

Superior borders of 2nd or 3rd ribs below

Question 23

Subcostal Innervation

Answer 23

Intercostal nerve

Question 24

Subcostal Action

Answer 24

Probably act in same manner as internal intercostal muscles

Question 25

Inferior Oblique (IO) Innervation

Answer 25

Oculomotor nerve (CN III)

Question 26

Inferior Oblique (IO) Action

Answer 26

Abducts, elevates, and laterally rotates eyeball

Question 27

Diaphragm origin

Answer 27

Xiphoid process, inner surface of ribs 7-12

Question 28

Diaphragm insertion

Answer 28

Central tendon of the diaphragm

Question 29

Diaphragm innervation

Answer 29

Phrenic nerve (C3-C5)

Question 30

Diaphragm action

Answer 30

Increases intrathoracic volume during inhalation