THORAX ABDOMEN AND PELVIS

Detailed explanation-1: -The primary function of the trachealis muscle is to constrict the trachea, allowing air to be expelled with more force, such as during coughing.

Detailed explanation-2: -The trachealis muscle relaxes during swallowing to facilitate the passage of food by allowing the esophagus to bulge into the lumen of the trachea, with the elastic layer preventing excessive distention of the lumen.

Detailed explanation-3: -Like the smooth muscle in other airway segments, the trachealis muscle is innervated by local parasympathetic ganglia. The ganglia in turn receive inputs from parasympathetic preganglionic neurons located in the medulla via nerve fibers carried by the vagus nerves.