Upper Respiratory Tract

The airway above the voice box — the nose, nasal cavity, sinuses, and pharynx (throat).

Parts

• Nose and nasal cavity — the main air intake.
• Paranasal sinuses — air-filled spaces in the skull around the nose.
• Pharynx — the shared passage for air and food, behind the nose and mouth.

What it does

• Conditions incoming air — warms, moistens, and filters it.
• Houses the sense of smell.
• Routes traffic — the pharynx directs air toward the larynx and food toward the esophagus.

Key idea

The upper tract is the body’s air-conditioning unit — by the time air reaches the lungs it is warm, humid, and largely clean.