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Muscles - Trunk
Muscles of the Trunk
| Term | Definition |
|---|---|
| external intercostals | origin: inferior border of each rib |
| external intercostals | insertion: superior border of next rib |
| external intercostals | action: elevate ribs |
| internal intercostals | origin: superior border of each rib |
| internal intercostals | insertion: inferior border of the preceding rib |
| internal intercostals | action: depress ribs |
| diaphragm | origin: xiphoid process, cartilages of ribs 4-10, and anterior surfaces of lumbar vertebrae |
| diaphragm | insertion: central tendinous sheet |
| diaphragm | action: contraction expands thoracic cavity, compresses abdominopelvic cavity |
| external oblique | origin: lower eight ribs |
| external oblique | insertion: linea alba and iliac crest |
| external oblique | action: compresses abdomen, depresses ribs, flexes or laterally flexes vertebral column |
| internal oblique | origin: illiac crest and adjacent connective tissues |
| internal oblique | insertion: lower ribs, xiphoid of sternum and linea alba |
| internal oblique | action: compresses abdomen, depresses ribs, flexes or laterally flexes vertebral column |
| transversus abdominis | origin: cartilages of lower ribs, iliac crest, and adjacent connective tissues |
| transversus abdominis | insertion: linea alba and pubis |
| transversus abdominis | action: compresses abdomen |
| rectus abdominis | origin: superior surface of pubis around symphysis |
| rectus abdominis | insertion: inferior surfaces of costal cartilages (ribs 5-7) and xiphoid process |
| rectus abdominis | action: depresses ribs, flexes vertebral column |