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Rectus Abdominis
- Origin: pubic crest; pubic symphysis
- Insertion: Cartilage of ribs 5 -7 and xyphoid process
- Actions: flexion of the trunk (insertion moves towards origin); tilts pelvis posteriorly (origin to insertion)
- Nonropy
- Superficial
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Quadratus Lumborum
- Origin: Posterior iliac crest; iliolumbar ligament
- Insertion: 12th rib; TVPs of L1 - L4
- Bilateral action: assists in trunk extension; fixes 12th rib during respiration
- Unilateral actions: ipsilateral lateral of trunk (insertion to origin); elevation of hip (really pelvic girdle; origin to insertion)
- Nonropy
- Very deep
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External Oblique
- Starts where serratus anterior stops
- Origin: External surface of lower 8 ribs
- Insertion: Anterior iliac crest and abdominal aponeurosis
- Bilateral action: flexion of trunk
- Unilateral actions: ipsilateral flexion of the trunk; contralateral rotation of the trunk (contracts down and across)
- Nonropy
- Superficial
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Internal Oblique
- Origin: Lateral inguinal ligament iliac crest; thoracolumbar aponeurosis
- Insertion: cartilage of lower 3 ribs; abdominal aponeurosis to linea alba
- Bilateral action: flexion of the trunk and compresses the abdominal contents
- Unilateral action: ipsilateral lateral flexion and rotation of the trunk
- Nonropy
- Deep to external obliques
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