What is the length and average diameter of the trachea?
- 10-11cm lomg
- average 2.5cm wide
What are the boundaries of the trachea?
- starts at C6
- ends at T4/5 (at the carina)
What is the trachea composed of that keeps the lumen patent?
c-shaped hyaline cartilage rings
What muscle alters the tracheal diameter?
trachealis muscle
Where is the trachealis muscle located?
posteriorly between the ends of the tracheal cartilages
Red = trachealis muscle
In the cervical region what is the trachea related to?
- sternohyoid muscle
- sternothyroid muscle
- isthmus of thyroid gland
- inferior thyroid vessels
- carotid sheath
- brachiocephalic trunk
- jugular venous arch
- recurrent laryngeal nerve
Where does the trachea enter the thoracic cavity?
through the thoracic inlet
Where does the left recurrent laryngeal nerve lie?
in the groove between the trachea and the oesphagus
At what level does the trachea divide into left and right principle bronchi?
T4/5 - sternal angle
Red = left recurrent laryngeal nerve
What areteries supply the trachea?
- inferior thyroid artery
- bronchial arteries
- tracheal branches of aorta
- mediastinal branches of internal thoracic artery
What veins drain the trachea?
- inferior thyroid vein (plexus)
- bronchial veins
What lymph nodes are related to the trachea?
- pre-tracheal lymph nodes
- paratracheal lymph nodes
What is the neural supply of the trachea
SNS = sympathetic trunk
PSNS = vagus nerve
How does the right main bronchus differ from the left? And why is this clinical important?
more verticle, shorter and wider
Foreign body aspiration
What do the main bronchi divide into?
lobar bronchi
How many lobar bronchi are there in each lung
LHS = 2
RHS = 3
What do the lobar bronchi divide into?
segmental bronchi
What do the segmantal bronchus pass to?
a broncho-pulmonary segment
How do the segmental bronchi alter diameter?
bronchi divide like a tree decreasing the diameter
What do segmental bronchi divide into?
terminal bronchioles
What are terminal bronchioles connected to?
respiratory bronchioles
How do bronchioles affect airflow?
cause the greatest resistance to air flow in the conducting passages
How many pulmonary alveoli is each respiratory bronchiole connected to?
~2-11
What do alveolar ducts open into?
alveolar sacs (clusters of pulmonary alveoli)
How many alveoli does each alveolar duct connect to?
~5-6
What is the main purpose of the alveoli?
large surface area for the diffusion and exchange of gases
What are the 3 surfaces of the lungs?
costal, diaphragmatic and mediastinal
What are the three margins of the lungs?
anterior, inferior and posterior
What is another name for the apex of the lung?
cupula
What feature is unique to the left lung
has a cardiac notch
How does the right lung compare tho the left
shorter but wider
How many lobes does each lung have?
Right = 3
Left = 2 + lingula
Red = oblique fissure
blue = horizontal fissure
Where does the phrenic nerve pass in relation to the lung roots?
anterior
Where does the vagus nerve pass in relation to the lung roots?
posterior
What is the root of the lung?
collection of structures that attach the lung structures in the mediastinum
What is the root of the lung covered by?
a sleeve of mediastinal pleura that reflects on the surface of the lung
What is contained within the root of the lung?
- pulmonary artery
- 2 pulmonary veins
- a main bronchis
- bronchial vessles
- nerves
- lymphatics
What is the function of the pulmonary ligament?
Allows the lungs to be mobile
What is the smallest functionally and structurally independent unit of the lungs?
bronchopulmonary segemnts
What does a bronchopulmonary segment have?
own branch of pulmonary artery, nerves and segmental (tertirary) bronchus
Red = pulmonary artery
green = segmental bronchus
blue = pulmonaruy vein
what are bronchopulmonary segments separated by?
Connective Tissue
Is there anastomosis between neighbouring bronchopulmonary segments?
NO
what shape are bronchopulmonary segments and what are they directed towards?
pyramid-shaped
their apicies are directed towards the hilum
Where do tributaries of the pulmonary vein and lymphatics tend to pass?
intersegmental septum
How many segments does each lung have?
10
What are the divisions of the right lung
Inferior = 5
Superior = 3
Middle = 2
What segments are present in the superior section of the right lung?
Apical (superior)
Anterior
Posterior
What segments are present in the middle section of the right lung?
Medial
Lateral
What segments are present in the inferior section of the right lung?
Apical (superior)
Medial
Lateral
Anterior
Posterior
What segements are present in the superior section of the left lung?
Apical (superior)
Anterior
Posterior
What segments are present in the lingula section of the left lung?
superior and inferior
What segments are present in the inferior section of the left lung?
Apical (superior)
Medial
Lateral
Anterior
Posterior
What is the only part of the left lung that makes contact with the diaphragm?
lingula
What is the main constituent of bronchioles?
mainly smooth muscle
little cartilage
Where are goblet cells not present in the respiratory tract?
In and distal to respiratory bronchioles
What is the function of type I alveolar cells?
permit diffusion
what is the function of type II alveolar cells?
produce surfactant that reduces the tendency for pulmonary alveoli to collapse
How many cells thick are each pulmonary alveolus? And what is the reason for this?
1 cell thick
Increased diffusion rate
What can cause of a distortion of the carina?
enlargement of tracheobronchial lymph nodes
tumour
What segment in which lobe is most prone to pneumonia and why?
apical segment of the inferior lobe
drops of the bronchial tree posteriorly
What is the lung tissue supplied by?
bronchial arteries
How many bronchial arteries are on the RHS and where do they orginate from?
one bronchial artery on the right
3rd posterior intercostal artery or superior posterior intercostal artery
How many bronchial arteries are on the LHS and where do they orginate from?
2 bronchial arteries on the left
aorta
what can pulmonary arerties anastomose with and where?
pulmonary arteries in the walls of the bronchioles
What is the function of pulmonary arteries?
carry de-oxygenated blood to the lungs at low pressure
Where do the pulmonary arteries arise from?
from the pulmonary trunk just below the sternal angle
What is the tract of the right pulmonary artery?
Passes anterior to the right primary bronchus and posterior to the ascending aorta and SVC
What two lymphatic organs drain into the pulmonary nodes?
- deep lymphatic pleuxs (running alongside the arteries and dividing bronchial tree)
- Superficial (sub-pleural) lymphatic plexus
where are the pulmonary nodes located?
in the hilum of the lung
Give the passage of lymph drainage from the pulmonary nodes
Black = left and right bronchomediastinal trunk
red = superior tracheobronchial
green = inferior tracheobronchial
blue = paratracheal
What is the nerve supply of the lungs?
supplied by the pulmonary plexuses around the main bronchi at the root of the lung
Where do the parasympathetic fibres arise from and what is their action?
from vagus
bronchoconstrictor, vasodilator and secretomotor
Where do sympathetic fibres arise from and what is their function?
sympathetic trunk
brnchodilator, vasocontrictor
What are the three main reasons a tracheostemy would be needed?
- laryngeal obstruction
- evcuation of excessive secretions
- Long-lasting artificial respiration
What type of incision is made for a tracheostemy?
vertical incision is made downwards from the cricoid cartilage
