Anatomy of the Trachea

• The trachea is a fibrocartilaginous tube of the lower respiratory tract
• It forms the trunk of the tracheobronchial tree, extending between the larynx and thorax
• The trachea consists of two parts: the cervical and the thoracic
• It ends at the level of sternal angle (T5) where it divides into two main bronchi, one for each lung
• The main function of the trachea is to transport air in and out of the lungs during breathing
• The trachea protects the respiratory tract by warming and moistening the air and propelling foreign particles upwards towards the pharynx for expulsion
• The trachea is composed of 16-20 tracheal cartilages anteriorly and tracheal muscle posteriorly
• The superior limit of the trachea is the inferior end of the larynx (cricoid cartilage and level of C6), and the inferior limit is the tracheal bifurcation (level of sternal angle and upper border of T5)
• Arterial blood supply to the trachea comes from tracheal branches of the inferior thyroid artery
• Venous drainage is through the inferior thyroid venous plexus
• Lymphatic drainage involves pretracheal nodes and paratracheal cervical and thoracic lymph nodes
• The trachea is a D-shaped fibrocartilaginous respiratory organ with 16-20 tracheal cartilages anterolaterally and fibromuscular wall posteriorly
• Histologically, the trachea consists of 4 layers: innermost lined by pseudostratified ciliated columnar epithelium, submucosal layer with mucus gland and smooth muscle, musculocartilaginous layer with cartilaginous rings and smooth muscle, and outer fibroelastic adventitia
• The trachea is divided into cervical and thoracic parts, with the cervical part beginning at the inferior border of the larynx (cricoid cartilage) and ending at the jugular notch of the sternum
• The thoracic part of the trachea is located within the superior mediastinum, beginning at the superior thoracic aperture and ending at the tracheal bifurcation
• The main bronchi branch off from the trachea at the tracheal bifurcation, with the right main bronchus being shorter, wider, and more vertically oriented compared to the left main bronchus
• Each main bronchus further divides into smaller intrapulmonary bronchi that supply the lungs
• Segmental bronchi aerate the bronchopulmonary segments, with the right side having 10-12 segmental bronchi and the left side having 8-10 segmental bronchi
• Intrasegmental (subsegmental) bronchi transport air deeper within the bronchopulmonary segments, branching off from segmental bronchi and terminating as pulmonary lobules and alveoli
• Tracheomalacia is a congenital anomaly affecting the tracheal cartilage rings, leading to softening and collapse of the trachea during inspiration and expiration
• Tracheomalacia may be associated with symptoms such as dyspnea, cough, stridor, wheezing, tachypnea, and in severe cases, apnea
• Management of tracheomalacia may involve tracheostomy to stent the airway or aortopexy to relieve the condition in most patients