Respiratory muscles of forced expiration vs quiet breathing
Core concept
- Quiet expiration is passive - stored elastic recoil of lung + chest wall; no muscle work
- Quiet inspiration is active - diaphragm ~70-75% of tidal volume, plus external intercostals, parasternal intercostals, scalenes (active even at rest)
- Forced expiration is active - two groups
- Abdominal wall (the principal expiratory muscles): rectus abdominis, external oblique, internal oblique, transversus abdominis
- inc intra-abdominal pressure -> pushes diaphragm cephalad
- Internal intercostals (interosseous part) - pull ribs down and in
- Abdominal wall (the principal expiratory muscles): rectus abdominis, external oblique, internal oblique, transversus abdominis
- Accessory inspiratory (recruited in distress): sternocleidomastoid, scalenes, trapezius, pectoralis minor, alae nasi
3 more sections, plus exam facts
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