Muscles that AID in respiration

Question 1

External intercostals

Answer 1

ORIGIN
Inferior border of rib.

INSERTION
The superior border rib below. Fibers run at a 45-degree angle lateral to medial.

ACTION
Elevation of the ribs during inhalation.

INNERVATION
Intercostal nerves.

Question 2

Internal intercostals

Answer 2

ORIGIN
Superior border of rib.

INSERTION
Inferior border of rib above. Fibers run at a 45 degree angle – medial to lateral.

ACTION
Depression of the ribs during exhalation (decreases space in thoracic cavity).

INNERVATION
Intercostal nerves.

Question 3

Diaphragm

Answer 3

ORIGIN
Inferior border of rib.

INSERTION
The superior border rib below. Fibers run at a 45-degree angle lateral to medial.

ACTION
Elevation of the ribs during inhalation.

INNERVATION
Intercostal nerves.

Internal Intercostals

ORIGIN
Superior border of rib.

INSERTION
Inferior border of rib above. Fibers run at a 45 degree angle – medial to lateral.

ACTION
Depression of the ribs during exhalation (decreases space in thoracic cavity).

INNERVATION
Intercostal nerves.

Diaphragm

ORIGIN
Upper lumbar vertebrae, lower six ribs, and xiphoid process.

INSERTION
Central tendon.

ACTION
Contracts and increases the capacity of the thoracic cavity during inspiration.

INNERVATION
Phrenic nerve.

Question 4

Serratus posterior superior

Answer 4

ORIGIN
Ligamentum nuchae and spinous processes of C7-T2.

INSERTION
Ribs 2-5.

ACTION
Elevates ribs during inhalation.

INNERVATION
Intercostal nerves

Question 5

Serratus posterior inferior

Answer 5

ORIGIN
Spinous proccesses of T11-L2.

INSERTION
Ribs 9-12.

ACTION
Depression of ribs. Antagonist to diaphragm.

INNERVATION
Intercostal nerves.