Which of the following muscle groups is considered muscles of inspiration?

a. External intercostal muscles

b. Internal intercostal muscles

c. External oblique muscles

d. Internal oblique muscles

Video transcript

Hi, everyone. Let's take a look at this practice problem together. Which of the following happens during the inspiration process. The answer options are a, the diaphragm relaxes B, the intercostal muscles contract. C, the rib cage collapses and D all of the above. So recall that inspiration is when we are breathing in air into the lungs. The answer options include the structures of the diaphragm, the intercostal muscles and the rib cage and these are all structures involved in breathing on the screen. I am putting up a table. The left column contains the three different structures listed in their own row and the next two columns are for exploration or breathing air out of the lungs and inspiration. Let's go through together and review what happens to each of our structures during expiration and inspiration. Now, recall that the diaphragm is a dome shaped muscle when it's relaxed, when it contracts it flattens and this helps to draw air in. So during inspiration, the diaphragm contracts and during expiration, the diaphragm relaxes. So option A is incorrect during inspiration, the diaphragm contracts. So we can eliminate option A. Now let's talk about the rib cage during expiration the rib cage collapses and its collapse helps to expel air out of the lungs. Now, during inspiration, the rib cage expands and that helps draw more air into the lungs. So, option C, the rib cage collapses is also an incorrect option. The rib cage expands during inspiration. So option C is incorrect. Option B, the intercostal muscles recall that these muscles are located in between the ribs and they contract during inspiration and they are relaxed during expiration. So the correct answer is option B, the intercostal muscles contract. All right, everyone. I hope you found this helpful and I'll see you soon for the next practice problem.