Muscles of Breathing: Diaphragm, Intercostals & Accessory Muscles
Primary Muscles
- Diaphragm: Dome-shaped muscle separating thorax and abdomen; contracts to inhale, relaxes to exhale.
- Intercostal Muscles: Between ribs.
- External intercostals: elevate ribs during inhalation.
- Internal intercostals: depress ribs during forced exhalation.
Accessory Muscles of Inspiration
Used during deep breathing or respiratory distress:
- Sternocleidomastoid
- Scalenes (elevate upper ribs)
- Pectoralis minor
- Serratus anterior
Accessory Muscles of Expiration
Used during forced exhalation (coughing, sneezing, exercise):
- Abdominal muscles (rectus abdominis, obliques, transversus abdominis)
- Quadratus lumborum
- Latissimus dorsi
Coordinated action of these muscles enables efficient ventilation.
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