Diaphragm and Intercostal Muscles
Describes the structure and function of the diaphragm and external/internal intercostal muscles in facilitating breathing movements.
What is Diaphragm and Intercostal Muscles?
A large, dome-shaped muscle located at the base of the thoracic cavity that plays a major role in breathing.
Key points
- Identify the diaphragm and intercostal muscles.
- Explain the mechanism of inspiration.
- Explain the mechanism of quiet expiration.
- Explain the mechanism of forced expiration.
Common exam trap
Confusing the roles of external and internal intercostal muscles.
Definitions
- Term
Diaphragm
- Meaning
A large, dome-shaped muscle located at the base of the thoracic cavity that plays a major role in breathing.
- Term
Intercostal Muscles
- Meaning
Muscles located between the ribs; external intercostals aid inspiration, and internal intercostals aid forced expiration.
- Term
Intrapulmonary Pressure
- Meaning
The pressure within the alveoli of the lungs.
- Term
Intrapleural Pressure
- Meaning
The pressure within the pleural cavity, between the visceral and parietal pleura.
Learning objectives
Identify the diaphragm and intercostal muscles.
Explain the mechanism of inspiration.
Explain the mechanism of quiet expiration.
Explain the mechanism of forced expiration.
Relate muscle action to changes in thoracic volume and intrapulmonary pressure.
Prerequisites
Basic understanding of the skeletal system (rib cage).
Knowledge of pressure gradients.
Understanding of muscle contraction and relaxation.
Common mistakes
Confusing the roles of external and internal intercostal muscles.
Not understanding that quiet expiration is passive.
Incorrectly associating diaphragm relaxation with increased thoracic volume.
Forgetting that abdominal muscles also aid in forced expiration.
Keywords
Diaphragm
Intercostal Muscles
Inspiration
Expiration
Ventilation
Thoracic Cavity
Intrapulmonary Pressure
Boyle's Law
Practice preview
Which of the following muscles contract during normal quiet inspiration?…
easy
What is the primary action of the diaphragm during inspiration?…
easy
Which sequence correctly describes the events during inspiration?…
medium