The shortest part of respiratory system is

A pharynx is a cone-shaped short passage which connects the oral and nasal cavities in the head to the oesophagus and larynx. It has three divisions the oropharynx which is connected to the oral cavity for intake of food, nasopharynx which is connected to nasal passage and laryngopharynx which is connected to voice box. Both circular and longitudinal muscles occur in the walls of this organ; the circular muscles form constrictions that help push food to the esophagus and prevent air from being swallowed, while the longitudinal fibres lift the walls of the pharynx during swallowing.