Trachea, Bronchial Tree and Lungs Flashcards
Where does the trachea run from?
C6 to T4/5 at the carina
What makes up the trachea?
- C shaped hyaline cartilages (keep lumen patent)
- trachealis muscle: posteriorly between ends of tracheal cartilages (alters tracheal diameter)
What are the relations of the trachea?
- sternohyoid muscle
- stermothyroid muscle
- isthmus of the thyroid gland
- inferior thyroid vessels
- carotid sheath
- brachiocephalic trunk
- jugular venous arch
- recurrent laryngeal nerve
Describe how the trachea enters the thoracic cavity
- enters through the thoracic inlet
- divides into left and right principal bronchi
Where does the left recurrent laryngeal nerve sit?
in the groove between the trachea and oesophagus
What arteries supply the trachea?
- inferior thyroid artery
- bronchial arteries
- tracheal branches of aorta
- mediastinal branches of ITA
What veins drain the trachea?
- inferior thyroid vein
- bronchial veins
What nerves supply the trachea?
- parasympathetics: vagus
- sympathetic trunks
What lymph nodes drain the trachea?
- pretracheal lymph nodes
- paratracheal lymph nodes
Describe the morphology of the principal bronchi and the clinical relevance of this
- right principal bronchi is more vertical, shorter and wider
- more likely for foreign body to enter right principal bronchi
What does the main bronchi divide into?
- lobar bronchi that subdivides into segmental bronchi
- segmental bronchus passes to a broncho-pulmonary segment
What do segmental bronchi lead to?
- terminal bronchioles
- connected to respiratory bronchioles
- bronchioles cause the greatest resistance to air flow in conducting passages
What do bronchioles lead to?
- connected to alveolar ducts
- ducts open into alveolar sacs which are clusters of pulmonary alveoli
- provides a very large surface area for diffusion of gases
What are the surfaces and margins of the lungs?
Surfaces:
- costal
- diaphragmatic
- mediastinal
Margins:
- anterior
- posterior
- inferior
What are the differences in shape between the right and left lung?
Right:
- 3 lobes separated by an oblique and horizontal fissure
- shorter but wider
Left:
- 2 lobes separated by an oblique fissure
- has a cardiac notch
What are the impressions for on the right lung?
- oesophagus
- SVC
- right atrium
- IVC
- pulmonary ligament
What are the impression for on the left lung?
- subclavian artery
- aortic arch
- left ventricle
- pulmonary ligament
Where does the vagus nerve pass the lungs?
posterior to the lung roots
What vessels are in the root of the lung?
- a pulmonary artery
- 2 pulmonary veins
- a main bronchus
- bronchial vessels
- nerves
- lymphatics
Describe the arrangement of the vessels in the root of the lungs
- main bronchi sit most posteriorly
- pulmonary arteries superior
- pulmonary veins inferior
What are the bronchopulmonary segments?
- sections of the lung with its own branch of pulmonary artery, nerves and segmental bronchus
- pyramid shaped with apices directed towards hilum
- separated by connective tissue
- no anastomosis between segments
Describe the divisions of the bronchopulmonary segments
- 10 segments on each side
- upper lobe: apical, anterior and posterior
- middle/lingula: medial and lateral
- lower lobe: apical, medial, lateral, anterior and posterior
Describe the histological features of the lungs
- little cartilage in bronchioles, mainly smooth muscle
- no goblet cells in and distal to bronchioles
- pseudostratified columnar epithelium in bronchi replaced by simple cuboidal epithelium in bronchioles
- wall of pulmonary alevoli one cell thick (for diffusion)
Type I and II alveolar cell
- type I: permit diffusion
- type II: produce surfactant (lowers tension) that reduces tendency for pulmonary alveoli to collapse
What can cause distortion of the carina seen in a bronchoscopy?
enlargement of the tracheobronchial lymph nodes
Why is the segmental bronchi more susceptible to pneumonia?
It drops off the bronchial tree posteriorly making it easier for infection to spread there
Describe the vascular supply of the lungs
- bronchial arteries:
- 1 on right from 3rd posterior IC artery/superior posterior IC artery
- 2 on the left from the aorta
- can anastomose with pulmonary arteries in walls of bronchioles
- pulmonary arteries: carry deoxygenated blood to the lungs at low pressure
Describe the vascular drainage of the lungs
- bronchial veins to azygos system
- pulmonary veins
Where does the right pulmonary artery sit?
- anterior to the right primary bronchus
- posterior to ascending aorta and SVC
Describe the lymph drainage of the lungs
- deep and superficial lymphatic plexus
- to pulmonary nodes
(to bronchopulmonary, to inferior and superior tracheobronchia to paratracheal along with posterior mediastinal, to bronchomediastinal lymph trunk with parasternal and anterior mediastinal)
Describe the nerve supply of the lungs
- pulmonary plexuses around main bronchi at root of the lung
- parasympathetic fibres: from vagus, synpase in plexus
- postganglionic fibres to bronchoconstrictor, vasodilator and secretomotor
- sympathetic fibres: from sympathetic trunk, synapse in sympathetic ganglia
- post ganglionic fibres to bronchodilator and vasodilator
In what 3 situations would you do a tracheostomy?
- to bypass an obstructed upper airway
- to clean and remove secretions from the airway
- to more easily, and usually more safely, deliver oxygen to the lungs.
