Medical Gross Anatomy
Anatomy Tables - Muscles
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Medical Gross Anatomy |
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Muscles of the Thoracic Region - Listed Alphabetically |
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| 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 | ){kind=spacer} |
| The material presented in these tables is
contained in the book: MedCharts Anatomy by Thomas R. Gest & Jaye Schlesinger Published by ILOC, Inc., New York Copyright © 1995, unauthorized use prohibited. |
The excellent editorial assistance of Dr. Pat Tank, UAMS is gratefully acknowledged. |
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| Copyright© 2000 Thomas R. Gest, PhD Unauthorized use prohibited. | |