Which accessory muscle plays a role in elevating the ribs during inhalation?

• A. Rectus abdominus
• B. External intercostals
• C. Pectoralis minor
• D. Transverse abdominus

Answer: (B)

The external intercostals are a group of muscles located between the ribs that primarily function during inhalation. When the diaphragm contracts and the chest expands, the external intercostals assist by elevating the ribs, which increases the volume of the thoracic cavity and allows air to fill the lungs. This elevation is crucial for effective ventilation, as it helps create a negative pressure that draws air in.

While other muscles, like the pectoralis minor, also contribute to rib movement, the external intercostals are specifically oriented to aid in rib elevation directly during the inhalation phase of breathing. Their role is essential for the mechanics of breathing, making them the primary accessory muscles for this action.