Merck Manual

Please confirm that you are not located inside the Russian Federation

Yes No
Leave this Site?

The link you have selected will take you to a third-party website. We do not control or have responsibility for the content of any third-party site.

Continue Cancel
honeypot link
Merck Manual
Consumer Version
The trusted provider of medical information since 1899
VIEW PROFESSIONAL VERSION
VIEW PROFESSIONAL VERSION

Enter search terms to find related medical topics, multimedia and more.

Advanced Search:

  • Use “ “ for exact phrases.
    • For example: “pediatric abdominal pain”
  • Use – to remove results with certain keywords.
    • For example: abdominal pain -pediatric
  • Use OR to account for alternate keywords.
    • For example: teenager OR adolescent

Health Topics & Chapters
Inside the Lungs and Airways

Inside the Lungs and Airways

Inside the Lungs and Airways

Brought to you by Merck & Co, Inc., Rahway, NJ, USA (known as MSD outside the US and Canada)—dedicated to using leading-edge science to save and improve lives around the world. Learn more about the Merck Manuals and our commitment to Global Medical Knowledge.


This icon serves as a link to download the eSSENTIAL Accessibility assistive technology app for individuals with physical disabilities. It is featured as part of our commitment to diversity and inclusion. M
This icon serves as a link to download the eSSENTIAL Accessibility assistive technology app for individuals with physical disabilities. It is featured as part of our commitment to diversity and inclusion. M
Copyright © 2023 Merck & Co., Inc., Rahway, NJ, USA and its affiliates. All rights reserved.