Thoracic Muscles

Question 0

Intercostales Externi

Answer 0

O: upper rib inferior boarder, outermost fibers
I: lower rib superior boarder
ACT: elevate ribs & stabilize intercostal spaces
INN: intercostal nerve (T2-12)

Question 1

Diaphragm

Answer 1

O: Costal -inter surface & adjacent of R6-12, Sternal -posterior side of xiphoid, Lumbar -two aponeurotic arches covering the external surface of the quadratus lumborum & psoas major muscles, right and left crus originating from L1-3
I: central tendon near center of done
ACT: lowers dome, increases vertical volume of lungs
INN: phrenic nerve (C3-5)

Question 2

Intercostales Interni

Answer 2

O: upper rib inferior boarder, run just under externi fibers
I: lower rib superior boarder
ACT: parasternal fibers-elevate ribs
Interosseous fibers-depresses ribs 
Both-stabilize intercostal spaces
INN: intercostal nerve (T2-12)

Question 3

Serratus Posterior Superior

Answer 3

O: ligamentum nuchae; spinous process of C7-T2/3
I: upper ribs
ACT: elevation of ribs
INN: ventral rami of upper 3-4 thoracic spinal nerves

Question 4

Serratus Posterior Inferior

Answer 4

O: Spinous process of T11-L2
I: lower 3-4 ribs
ACT: pulls lower ribs inferiorly; helps to stabilize diaphragm
INN: ventral rami of lower thoracic (9-12) spinal nerve

Question 5

Levator Costarum

Answer 5

O: ends of transverse processes (C7-T11)
I: external surface of ribs between tubercle and angle
ACT: increases intrathoracic volume by elevating ribs
INN: dorsal rami of adjacent thoracic spinal nerve roots (C7-11)

Question 6

Transverse Thoracis

Answer 6

O: inner surface of lower third of body of sternum & xiphoid process
I: inner surface of sternocostal joints of R2-6
ACT: decreases thoracic volume by depressing ribs
INN: adjacent intercostal nerves