Tracheobronchial Tree

Question 1

What is the trachea?

Answer 1

Fibrocartilaginous tube of the lower respiratory tract

10-11 cm long

Question 2

Extent of the trachea

Answer 2

From the larynx to sternal angle (T5) where it splits into two primary bronchi

Question 3

Structure of the trachea

Answer 3

16-20 tracheal cartilages anterolaterally and a fibromuscular wall posteriorly

Question 4

Structure of the tracheal cartilages

Answer 4

Formed from hyaline cartilage and interconnected by fibroelastic tissue

Question 5

Function of the tracheal cartilage structure

Answer 5

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

Question 6

Regions of the trachea

Answer 6

Cervical and thoracic

Question 7

Extent of cervical region of trachea

Answer 7

From cricoid cartilage at the inferior border of the larynx (C6) to the jugular notch

Question 8

Extent of the thoracic region of trachea

Answer 8

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)

Question 9

Number of segmental bronchi

Answer 9

Right lung: 10-12 segmental bronchi
Left lung: 8-10 segmental bronchi

Question 10

What are intrasegmental/subsegmental bronchi?

Answer 10

Transport air even deeper within the bronchopulmonary segments
Each segmental bronchus provides approximately fifteen intrasegmental bronchi

Question 11

Anterior relations of the cervical part of the trachea

Answer 11

Deep to superficial:
The visceral cervical fascia
The isthmus of thyroid gland
Pretracheal lymph nodes
The sternohyoid and sternothyroid muscles
The jugular venous arch

Question 12

Anterior relations of the thoracic part of the trachea

Answer 12

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

Question 13

Posterior relations of the thoracic part of the trachea

Answer 13

Esophagus

Question 14

Lateral relations of the thoracic part of the trachea

Answer 14

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

Question 15

Arterial blood supply of the trachea

Answer 15

Inferior thyroid arteries (from the thyrocervical trunk)

Question 16

Venous drainage of the trachea

Answer 16

Drained to the inferior thyroid venous plexus (which empties into the brachiocephalic veins)

Question 17

Lymphatic drainage of the trachea

Answer 17

Drained into the pretracheal and paratracheal (cervical and thoracic) lymph nodes that empty into the deep cervical lymph nodes

Question 18

Innervation of the trachea

Answer 18

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

Question 19

What is tracheomalacia?

Answer 19

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

Question 20

Symptoms of tracheomalacia

Answer 20

Respiratory distress such as dyspnea, cough, and wheezing
In severe tracheal collapse, it can even manifest with the cessation of breathing (apnea)

Question 21

How is apnea caused by severe tracheomalacia managed?

Answer 21

Tracheal tube or airway stents are used to bypass the obstruction and maintain the trachea open