The upper respiratory tract or upper airway primarily refers to the parts of the respiratory system lying outside of the thorax or above the sternal angle. Another definition commomly used in medicine is the airway above the glottis or vocal cords. Some specify that the glottis (vocal cords) is the defining line between the upper and lower respiratory tracts; yet even others make the line at the cricoid cartilage.
Upper respiratory tract infections are among the most common infections in the world.
Read more about Upper Respiratory Tract: Components, Role in Respiration
Famous quotes containing the words upper and/or tract:
“Surely you wouldn’t grudge the poor old man
Some humble way to save his self-respect.
He added, if you really care to know,
He meant to clear the upper pasture, too.”
—Robert Frost (1874–1963)
“My only companions were the mice, which came to pick up the crumbs that had been left in those scraps of paper; still, as everywhere, pensioners on man, and not unwisely improving this elevated tract for their habitation. They nibbled what was for them; I nibbled what was for me.”
—Henry David Thoreau (1817–1862)