| Rectus Abdominus | Origin: Pubic Bone
Insertion: Sternum and costal Cartilages of ribs 5-7
Action: Compress abdominal viscera and flex trunk
innervation: Thoracic and Ventral Rami |
| External Oblique | Origin: Lower 8 ribs
Insertion: Iliac Crest and Linea Alba (rectus Sheath)
Action: Compress/support abdominal Viscera (organs), flex and rotate trunk
Innervation: Thoracic Ventral Rami |
| Internal Oblique | Origin: thoracolumbar Fascia, iliac crest, Inguinal Ligament
Insertion: Ribs 10-12, Linea Alba (rectus Sheath)
Action: Compress/support Abdominal Viscera (organs), flex and rotate trunk
Innervation: Thoracic and Lumbar ventral rami |
| Transversus Abdominus | Origin: Thoracolumbar Fascia, Iliac Crest, Lower 6 ribs, Inguinal Ligament
Insertion: Linea Alba (rectus Sheath)
Action: Compress and support abdominal viscera
Innervation: thoracic and lumbar ventral Rami |
| Quadratus Lumborum | Origin: Iliac Crest
Insertion: Transverse Processes of Lower Lumbar Vertebrae, Rib 12
Action: Extend Vertebral Column (bilaterally), Laterally flex vertebral Column (unilaterally)
Innervation: Thoracic and Lumbar Ventral Rami |
| Diaphragm *Not Hypaxial* | Origin: Xiphoid Process, Coastal Cartilages (ribs 7-12), Lumbar Vertebrae, and intervertebral discs
Insertion: The central tendon
Action: Contraction moves inferiorly and decreases pressure in thoracic cavity (INHALATION)
Innervation: Phrenic Nerve |
| External Intercostals | Origin: 11 pairs of muscles attached to ribs (intercostal spaces)–same direction as the external Oblique
Insertion: Same as origin
Action: Elevates Rib cage
Innervation: Thoracic ventral Rami |
| Internal Intercostals | Origin: 11 pairs of muscles attached to ribs (intercostal Spaces)–Same direction as INTERNAL oblique
Insertion: Same as s origin
Action: Depress rib cage (forces expiration)
Innervation: Thoracic Ventral Rami |
| Transversus Thoracis | Origin: Posterior surface of Sternum
Insertion: Internal surface of Costal Cartilages 2-6
Action: Mild depression of ribs (exhale)
Innervation: Thoracic Ventral Rami |
| Scalenes *Not hypaxial* | Origin: Transverse Processes of Cervical Vertebrae
Insertion: Ribs 1 and 2
Action: Assists in deep inhalation. Flex, laterally, and rotate head
Innervation: Cervical Spinal Nerves |
