Muscles of Thorax

Question 1

Origin of the Diaphragm

Answer 1

Xphoid process
Costal Margin
Fascia over quadratus lumborum and psoas major
Vertebral bodies of L1-L3
Lateral & medial arcuate ligaments

Question 2

Insertion of Diaphragm

Answer 2

Central tendon of diaphragm

Question 3

Action of Diaphragm

Answer 3

Pushes abdominal viscera inferiorly increasing the volume of thoracic cavity (inhalation)

Question 4

Origin of External Intercostals

Answer 4

Lower border of a rib within an intercostal space

Question 5

Insertion of External Intercostals

Answer 5

Upper border of rib below, coursing downward and medially

Question 6

Action of External Intercostals

Answer 6

Keeps the intercostal space from blowing out or sucking in during respiration

Question 7

Origin of Innermost Intercostals

Answer 7

Upper border of a rib

Question 8

Insertion of Innermost Intercostals

Answer 8

Fibers course up and medially to insert on the inferior margin of the rib above

Question 9

Action of Innermost Intercostals

Answer 9

Keep the intercostal space from blowing out or sucking in during respiration

Question 10

Origin of Internal Intercostals

Answer 10

Upper border of rib above

Question 11

Action of Internal Intercostals

Answer 11

Keep the intercostal space from blowing out or sucking in during respiration

Question 12

Insertion of Internal Intercostals

Answer 12

Lower border of rib above, coursing up and medially

Question 13

Origin of Levatores Costarum

Answer 13

TVP’s of C7-T11

Question 14

Insertion of Levatores Costarum

Answer 14

Rib below its origin, medial to the angle

Question 15

Action of Levatores Costarum

Answer 15

Elevates rib

Question 16

Origin of Serratus Posterior Inferior

Answer 16

Thoracolumnar fascia, SPs of T11-12

Question 17

Insertion of Serratus Posterior Inferior

Answer 17

Ribs 9-12, latearl to the angles

Question 18

Action of Serratus Posterior Inferior

Answer 18

Pulls down lower ribs

Question 19

Origin of Serratus Posterior Superior

Answer 19

Nuchal ligament, Sp’s of C7-T3

Question 20

Insertion of Serratus Posterior Superior

Answer 20

Ribs 1-4, lateral to the angles

Question 21

Action of Serratus Posterior Superior

Answer 21

Elevates the upper ribs

Question 22

Origin of Subcostalis

Answer 22

Angles of ribs

Question 23

Insertion of Subcostalis

Answer 23

Angle of a rib 2-3 ribs above origin

Question 24

Action of Subcostalis

Answer 24

Compresses the intercostal space

Question 25

Origin of Transversus Thoracis

Answer 25

Posterior surface of the sternum

Question 26

Insertion of Transversus Thoracis

Answer 26

Inner surface of costal cartilage 2-6

Question 27

Action of Transversus Thoracis

Answer 27

Compresses the thorax for forced expiration