Often called the windpipe, the trachea is the passageway of air to the lungs. It is a 10-12 cm long flexible cylindrical tube, about 1 inch in diameter, which extends as an elastic pipe in front of the esophagus. By its structure, it maintains the air flow. It consists of 16-20 horseshoe-shaped rings composed of hyaline cartilage (the tracheal cartilages) and a membranous back wall composed of connective tissue and tracheal muscle. Rings of cartilage hold the trachea open. The cartilages have the shape of a C, where the open portion faces the esophagus. The tracheal muscles are interconnected by collagenous connective tissue (anular ligaments). The wall of the trachea is lined with mucous membrane and there are many hairlike cilia fanning upward toward the throat, moving dust particles that have been caught in the mucous membrane, thus preventing them form reaching the lung. The innermost layer of the trachea is called ciliated epithelium. 1,3
At its lower end it divides into two tubes, the left and right principal bronchi. The right principal bronchus almost continues the course of the trachea, the left one turns more sideways. Each bronchus enter the lung of its own side. The right bronchus is wider and shorter than the left and its direction is almost identical with that of the trachea. This is why aspirated foreign bodies usually get into the right principal bronchus.2,3 At its upper end, the trachea joins the larynx, also known as the voicebox.
Tracheal Diseases & Disorders
- Tracheal Stenosis, narrowing of the trachea
- Tracheal Neoplasms, tracheal tumors
- Tracheitis, inflammation of the trachea.
- Tracheomalacia, softening of the tracheal cartilage.
- Tracheobronchomegaly, congenitally enlarged size of the trachea and bronchi.
- Tracheoesophageal Fistula, a congenital abnormality in which the baby is born with an abnormal passage that connects the trachea and the esophagus
Tracheal Diseases & Disorders in Dogs
Obstructive disorders of the canine trachea include tracheal collapse, tracheal hypoplasia, segmental stenosis (narrowing of the trachea), inflammatory diseases, tumors, and tracheal compression.
Tracheal collapse is an acquired disorder in middle-aged to old dogs of toy breeds, which is characterized by a "goose honk" cough and difficulty breathing of varying degree.
Tracheal hypoplasia is a congenital disorder seen primarily in young brachicephalic dogs, such as pugs. The condition is associated with chronic respiratory distress and coughing and recurrent upper respiratory tract infections.5
Tracheal stenosis is narrowing of the trachea which may be congenital in small breeds, or may be acquired from previous tracheal trauma (bite wound). Narrowing can also be caused by inflammation or fibrosis (replacement of the normal tissue by fibrous tissue).6
Tracheal neoplasia is uncommon. Tumor types include squamous cell carcinoma, lymphosarcoma, adenocarcinoma, osteoma, osteosarcoma, chondroma, chondrosarcoma, and leiomyoma. Tracheal masses result in difficulty breathing and raspy respiration. treatment may involve surgical removal or chemotherapy.7
1. Thieme atlas of anatomy, Volume 2. Michael Schünke, Erik Schulte, Udo Schumacher, Lawrence M. Ross, Edward D. Lamperti, Markus Voll, Karl Wesker
2. Color Atlas and Textbook of Human Anatomy: Internal Organs. Werner Kahle, Helmut Leonhardt, Werner Platzer
3. Chemical exposure and toxic responses. Stephen K. Hall, Joanna Chakraborty, Randall J. Ruch
4. Anatomy Coloring Workbook. I. Edward Alcamo, John Bergdahl
5. Veterinary pathophysiology. Robert H. Dunlop, Charles-Henri Malbert
6. Radiographic interpretation for the small animal clinician. Jerry M. Owens, Darryl N. Biery
7. Small animal internal medicine. Darcy H. Shaw, Sherri L. Ihle