Aspiration Pneumonia and Related Syndromes Augustine S. Lee, MD, Jay H. Ryu, MD  Mayo Clinic Proceedings  Volume 93, Issue 6, Pages 752-762 (June 2018) DOI: 10.1016/j.mayocp.2018.03.011 Copyright © 2018 Mayo Foundation for Medical Education and Research Terms and Conditions

Figure Schematic of the anatomic barriers and protective defenses before gastroesophageal refluxate can reach the lungs and cause disease. LES = lower esophageal sphincter; UES = upper esophageal sphincter; ↓ = factor protective against aspiration; ↑ = factor favoring aspiration and disease. Mayo Clinic Proceedings 2018 93, 752-762DOI: (10.1016/j.mayocp.2018.03.011) Copyright © 2018 Mayo Foundation for Medical Education and Research Terms and Conditions