Question

What are the muscles involved in expiration and the abdominal skeleton?

1) External intercostal muscles
2) Internal intercostal muscles
3) Diaphragm
4) D. Rectus abdominus
5) Transversus abdominis

Answer 1

For expiration, the internal intercostal muscles and abdominal muscles like the rectus abdominis and transversus abdominis are primarily responsible. The external intercostal muscles facilitate inspiration, not expiration.

Step-by-step explanation:

The muscles involved in expiration mainly include the internal intercostal muscles and the abdominal muscles such as the rectus abdominis and the transversus abdominis. During forced expiration, these muscles contract to reduce the volume of the thoracic cavity, which increases the pressure inside the lungs, causing air to be expelled. The diaphragm, which is the primary muscle for breathing, relaxes during expiration. The external intercostal muscles are primarily involved in inspiration rather than expiration.