Tracheobronchial Tree Flashcards
What is the trachea?
Fibrocartilaginous tube of the lower respiratory tract
10-11 cm long
Extent of the trachea
From the larynx to sternal angle (T5) where it splits into two primary bronchi
Structure of the trachea
16-20 tracheal cartilages anterolaterally and a fibromuscular wall posteriorly
Structure of the tracheal cartilages
Formed from hyaline cartilage and interconnected by fibroelastic tissue
Function of the tracheal cartilage structure
Support the trachea and keep it open during pressure changes that accompany air ventilation
The trachealis muscle in the posterior wall, make the cartilages appear as incomplete C-shaped rings
The structure of its wall makes the trachea sufficiently flexible and elastic to permit the transient expansion of the esophagus during swallowing
Regions of the trachea
Cervical and thoracic
Extent of cervical region of trachea
From cricoid cartilage at the inferior border of the larynx (C6) to the jugular notch
Extent of the thoracic region of trachea
Begins from the superior thoracic aperture and ends at the tracheal bifurcation
The bifurcation can be located anywhere between the levels of the fourth and seventh thoracic vertebrae (often at the sternal angle)
Number of segmental bronchi
Right lung: 10-12 segmental bronchi
Left lung: 8-10 segmental bronchi
What are intrasegmental/subsegmental bronchi?
Transport air even deeper within the bronchopulmonary segments
Each segmental bronchus provides approximately fifteen intrasegmental bronchi
Anterior relations of the cervical part of the trachea
Deep to superficial:
The visceral cervical fascia
The isthmus of thyroid gland
Pretracheal lymph nodes
The sternohyoid and sternothyroid muscles
The jugular venous arch
Anterior relations of the thoracic part of the trachea
The inferior thyroid veins, manubrium of sternum and attachments of sternohyoid and sternothyroid muscles
The brachiocephalic trunk and left common carotid artery
The aortic arch, left brachiocephalic vein, cardiac plexus and paratracheal thoracic lymph nodes
Posterior relations of the thoracic part of the trachea
Esophagus
Lateral relations of the thoracic part of the trachea
Right side - Right vagus nerve, right brachiocephalic vein, superior vena cava and azygos vein
Left side - Aortic arch, left recurrent laryngeal nerve, left common carotid artery and left subclavian artery
Arterial blood supply of the trachea
Inferior thyroid arteries (from the thyrocervical trunk)
Venous drainage of the trachea
Drained to the inferior thyroid venous plexus (which empties into the brachiocephalic veins)
Lymphatic drainage of the trachea
Drained into the pretracheal and paratracheal (cervical and thoracic) lymph nodes that empty into the deep cervical lymph nodes
Innervation of the trachea
Innervation from the pulmonary plexus
Parasympathetic supply originates from the recurrent laryngeal nerves (branches of the vagus nerve)
Sympathetic supply is provided by the sympathetic trunks
What is tracheomalacia?
Tracheomalacia is a congenital anomaly affecting the development of the tracheal cartilage rings
Tracheal cartilages become abnormally soft and cannot keep the trachea open and it continuously collapses during inspiration and expiration
Affected area can span only a few cartilages or affect the entire trachea
Symptoms of tracheomalacia
Respiratory distress such as dyspnea, cough, and wheezing
In severe tracheal collapse, it can even manifest with the cessation of breathing (apnea)
How is apnea caused by severe tracheomalacia managed?
Tracheal tube or airway stents are used to bypass the obstruction and maintain the trachea open
