Intercostal muscles function.

Intercostal muscles function.

• A. Muscles which move the rib cage during breathing
• B. Muscles that move the hip
• C. Muscles that move the wrist
• D. Muscles that extend the knee

Answer: (A)

Intercostal muscles lie between the ribs and move the rib cage to change the size of the thoracic cavity during breathing. By lifting and expanding the ribs (external intercostals) on inhalation, the chest volume increases and air is drawn into the lungs; during forced exhalation, the internal intercostals help lower the ribs to decrease chest volume and push air out. This key role in ventilation is why they’re described as muscles that move the rib cage during breathing. They don’t govern movements of the hip, wrist, or knee, which involve different muscle groups.

Intercostal muscles lie between the ribs and move the rib cage to change the size of the thoracic cavity during breathing. By lifting and expanding the ribs (external intercostals) on inhalation, the chest volume increases and air is drawn into the lungs; during forced exhalation, the internal intercostals help lower the ribs to decrease chest volume and push air out. This key role in ventilation is why they’re described as muscles that move the rib cage during breathing. They don’t govern movements of the hip, wrist, or knee, which involve different muscle groups.