Internal Intercostals

• The Intercostals

  • Pass between adjacent ribs
  • 11 pairs between ribs 1 to 12 in the intercostal space
  • Arranged in 3 layers
  • Outer layer – external intercostals
  • Middle layer – internal intercostals
  • Deep layer – innermost intercostal
• Internal Intercostals:

  • Deep to external intercostals

  A) internal intercostals

  
• Origin:

  • From inferior border of rib above

  A) internal intercostals

  
• Insertion:

  • superior border of rib below

  A) internal intercostals

  
• Direction:

  • Fibres pass obliquely downwards and backwards

  A) internal intercostals

  
• Action:

  • forced expiration

  A) internal intercostals