NO GUESSING AS GUESSING GETS 0 KARMA Which of the following are expiratory muscl
ID: 27205 • Letter: N
Question
NO GUESSING AS GUESSING GETS 0 KARMA
Which of the following are expiratory muscles?
A. The external intercostals
B. The scalenes
C. The abdominals
D. The sternocleidomastoids
E. The diaphragm
Explanation / Answer
The correct answer is C, the abdominals. The other muscles listed are muscles of inspiration: Diaphragm>External intercostals>scalenes/sternocleidomastoids (in order of importance). Although the abdominals are listed and are the correct answer, they are only used upon forced expiration, and they aren't nearly as important as the internal intercostals (which weren't listed as a possible answer). Because of the mechanics of our lung and ribcage, normal expiration is usually a passive process (pay attention to your normal breathing, and you'll notice this). You have to actively use your diaphragm and external intercostals to inspire, and then if you just relax after taking a breath in, you'll exhale. However, try forcing air out, and you'll notice that your ribcage and abdominal muscles will tense - that's your internal intercostals and your abdominals working. --Hope that helps.
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