Final answer:
The carina of the trachea, which is a sensitive area with specialized nervous tissue, triggers a violent cough reflex when in contact with foreign objects to expel them from the respiratory tract.
Step-by-step explanation:
The most violent coughing is initiated when foreign objects come into contact with the carina of the trachea. The carina is a raised structure located at the point where the trachea branches into the right and left primary bronchi. This area is sensitive and has specialized nervous tissue that triggers a violent cough reflex if irritated by a foreign body such as food. Whilst the trachea is lined with pseudostratified ciliated columnar epithelium that contains mucus-producing goblet cells, and its structure is supported by C-shaped cartilaginous rings, it is the carina specifically that plays a crucial role in initiating the cough reflex to expel the offending objects from the respiratory tract.
The mucosa, which is composed of pseudostratified ciliated columnar epithelium that contains goblet cells, is the layer visible in the cross-section of tracheal wall tissue between the hyaline cartilage and the lumen of the trachea.