Internal oblique

Anatomy

Position

• Deep to external oblique
• Superifical to transversus abdominis

Origin

• Lateral 2/3 of inguinal ligament
• Crista iliaca
• Thoracolumbar fascia

Insertion

• Ribs 10-12
• Abdominal aponeurosis

Main function

• Trunk
  • Flexion
  • Lateral flexion
  • Ipsilateral rotation
• Pelvis
  • Posterior tilt

Secondary function

• Pelvis
  • Elevation
  • Contralateral rotation
• Abdominal content
  • Compression

Segmental nerve innervation

• Intercostal nerves

Arterial supply

• Subcostal and posterior intercostal arteries

Symptoms

• Postural distortion of pelvis
• Dysfunctional gait
• Loss of abdominal tone
• Gas, bloating, belching, heartburn
• Vomiting, diarrhea

Muscle type

• Phasic
  • Weakens when overactivated

Muscle attachment zones

Spiral line

• Splenius capitis and cervicis
• Rhomboideus major and minor
• Serratus anterior
• External oblique, abdominal aponeurosis, linea alba
• Internal oblique
• Tensor fascia latae
• Iliotibial tract
• Tibialis anterior
• Peroneus longus
• Biceps femoris
• Sacrotuerous ligament
• Sacrolumbar fascia
• Erector spinae