Respiratory Muscles

• Serratus posterior superior
  • Bony Attachments:
    • 1. Ligamentum nuchae, SP C7-T3
    • 2. Ribs 2-5 beyond rib angle
  • Innervation: T1-T4 spinal nerves
  • Arterial Supply: Post. intercostal a.
  • Action: Raises the upper ribs
• Serratus posterior inferior
  • Bony Attachments:
    • 1. Thoracodorsal fascia
    • 2. Ribs 9-12
  • Innervation: T9-T12 spinal nerves
  • Arterial Supply: Post. intercostal a.
  • Action: Depresses the lower four ribs
• Diaphragm
  • Innervation: Phrenic nerve
  • Arterial Supply: Ant. portion: Musculophrenic a.; Lat. portion: Post. intercostal a.; Post. portion: Superior phrenic a.; Central portion: Pericardiophrenic a.
  • Action: Pulls down to increase volume of thoracic cage
  • Sternal part
    • Bony Attachments:
      • 1. Post. aspect of xiphoid process of sternum
      • 2. Central tendon of diaphragm
  • Costal Part
    • Bony Attachments:
      • 1. Inferior six ribs at costal margins
      • 2. Central tendon of diaphragm
  • Lumbar part
    • Bony Attachments:
      • 1. Lumbar vertebrae by 2 crura and arcuate ligaments
      • 2. Central tendon of diaphragm
• Levator costae
  • Bony Attachments:
    • 1. 12 pairs from TP C7-T1-11
    • 2. Tubercle angle on outer surface of rib below
  • Innervation: Spinal nerves T1-12
  • Arterial Supply: Post. intercostal a.
  • Action: Elevates ribs in inspiration
• External intercostal
  • Bony Attachments:
    • 1. Shaft of rib just lateral to tubercle
    • 2. Runs obliquely, inferiorly and anteriorly to the rib
  • Innervation: Intercostal nerves
  • Arterial Supply: Intercostal a.
  • Action: Elevates ribs (assist during inspiration)
• Internal intercostal
  • Bony Attachments:
    • 1. Costal groove to superior rib
    • 2. Superior margin of inferior rib
  • Innervation: Intercostal nerves
  • Arterial Supply: Intercostal a.
  • Action: Depresses ribs (assist during expiration)
• Innermost intercostal
  • Bony Attachments:
    • 1. Inferior border of ribs
    • 2. Superior border of ribs
  • Innervation: Intercostal nerves
  • Arterial Supply: Intercostal a.
  • Action: Probably elevates ribs
• Transversus thoracis
  • Bony Attachments:
    • 1. Xiphoid process and inferior part of the body of the sternum
    • 2. 2-6 costal cartilages
  • Innervation: Intercostal nerves
  • Arterial Supply: Intercostal a.
  • Action: Depresses 2-6 ribs