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:
“The first to strike will gain the upper hand.”
—Chinese proverb.
“When the State wishes to endow an academy or university, it grants it a tract of forest land: one saw represents an academy, a gang, a university.”
—Henry David Thoreau (1817–1862)