Muscles of the Thoracic Region - Listed Alphabetically
|
Muscle |
Origin |
Insertion |
Action |
Innervation |
Artery |
Notes |
Image |
diaphragm |
xiphoid process, costal margin, fascia over the quadratus lumborum and psoas
major mm.(lateral & medial arcuate ligaments), vertebral bodies L1-L3 |
central tendon of the diaphragm |
pushes the abdominal viscera inferiorly, increasing the volume of the thoracic
cavity (inspiration) |
phrenic nerve (C3-C5) |
musculophrenic a., superior phrenic a., inferior phrenic a. |
left crus attaches to the L1-L2 vertebral bodies, the right crus attaches
to the L1-L3 vertebral bodies |
|
external intercostal |
lower border of a rib within an intercostal space |
upper border of the rib below, coursing, downward and medially |
keeps the intercostal space from blowing out or sucking in during respiration |
intercostal nerves (T1-T11) |
intercostal a. |
11 in number; they extend from the tubercle of the rib to the costochondral
junction; continuous with the external intercostal membrane anteriorly |
|
innermost intercostal |
upper borders of a rib |
fibers course up and medially to insert on the inferior margin of the rib
above |
keeps the intercostal space from blowing out or sucking in during respiration |
intercostal nerves (T1-T11) |
intercostal a. |
innermost intercostal mm. have the same fiber direction as the internal
intercostal mm., the only difference being that they lie deep to the intercostal
neurovascular bundle |
|
internal intercostal |
upper border of a rib |
lower border of rib above, coursing up and medially |
keeps the intercostal space from blowing out or sucking in during respiration |
intercostal nerves (T1-T11) |
intercostal a. |
11 in number; they extend from the margin of the sternum to the angle of
the rib; continuous posteriorly with the internal intercostal membrane |
|
levatores costarum |
transverse processes C7-T11 |
rib below its origin, medial to the angle |
elevates the rib |
dorsal primary rami of spinal nerves C7-T11 |
deep cervical a., intercostal aa. |
these are fairly small and insignificant muscles |
|
subcostalis |
angle of ribs |
angle of a rib 2-3 ribs above origin |
compresses the intercostal spaces |
intercostal nerves |
intercostal a. |
subcostalis, transversus thoracis & innermost intercostal mm. make up the
deepest intercostal muscle layer |
|
transversus thoracis |
posterior surface of the sternum |
inner surfaces of costal cartilages 2-6 |
compresses the thorax for forced expiration |
intercostal nerves 2-6 |
internal thoracic a. |
transversus thoracis, subcostalis & innermost intercostal mm. make up the
innermost intercostal muscle layer |
|