Trachea, Bronchial tree and lungs Flashcards
How long is the trachea?
10-11cm long
How wide is the trachea?
2.5cm
Where does the trachea start?
C6
Where does the trachea end?
- Intervertebral disc between T4/5
- At the carina
- At the sternal angle
Describe the structure of the trachea
- C shaped hyaline cartilage
- Connected by ligaments and membranes
- Trachealis muscle (posteriorly towards the ends of the tracheal muscle) alters the tracheal diameter (Smooth muscle so under autonomic control)
Red arrow
Trachealis muscle
What is the trachea related to in the cervical region?
- Sternothyroid muscle
- Sternohyoid muscle
- Isthmus of the thyroid gland
- Inferior thyroid muscles
- Carotid sheath
- Brachiocephalic trunk
- Jugular venous arch
- Recurrent laryngeal nerve (between the trachea and oesophagus)
How does the trachea enter the thoracic cavity?
Through the thoracic inlet
Where is the left recurrent laryngeal nerve?
In the groove between the trachea and the oesophagus
What does the trachea divide into and at what level?
- Into left and right principle bronchi
- Sternal angle (T4/5 intervertebral disc)
What is the difference between the principle bronchi?
The right is slightly more vertical, shorter and wider
What do the lobar bronchi divide into?
segmental bronchi
What happens to the bronchioles as you move distally?
- number increases
- Diameter decreases
What do the segmental bronchi become?
Terminal bronchi
What do the terminal bronchi become?
Respiratory bronchioles
What causes the greatest resistance to flow in the conducting passages?
Bronchioles
What do respiratory bronchioles open into?
- Alveolar ducts
- Open in to alveolar sacs
What do respiratory bronchioles open into?
- Alveolar ducts
- Open in to alveolar sacs
What are the surfaces of the lung?
- Costal: anterior and lateral
- Diaphragmatic: inferior
- Mediastinal: medial
What are the margins of the lung?
- Anterior
- Posterior
- Inferior
What is another name for the apex of the lung?
Cupula
Describe the shapes of the right and left lung
- Right is shorter and wider (due to the liver)
- Left has cardiac notch and lingula
Lobes of the right lung
- Superior (upper)
- Middle
- Inferior (lower)
Lobes of the left lung
- Upper
- Lower
Fissures of the right lung
- Oblique
- Horizontal
Fissures of the left lung
• Oblique
What structures are located in the root of the lung?
- Pulmonary artery
- 2 Pulmonary veins
- A main bronchus
- Bronchial vessels
- Nerves
- Lymphatics
What is the root covered by?
Sleeve of mediastinal pleura that reflects onto the surface of the lung
What is the pulmonary ligament
The pleura that has extended inferiorly below the root of the lung- it is not tight
• Allows the lungs to be slightly mobile
What are bronchopulmonary segments?
- Smallest functionally and structurally independent unit
- Section of lung with its own branch of pulmonary artery, nerves and segmental bronchus
- there is no anastomosis between segments
• They block the spread of disease
What is the shape of the bronchopulmonary segments?
- Pyramid shaped
- Apices towards the hilum
What separates the bronchopulmonary segments?
Connective tissue
Red arrow
Pulmonary artery
Green arrow
Segmental tertiary bronchus
Blue arrow
Pulmonary vein
In the bronchopulmonary segments, where do the pulmonary vein and lymphatics pass?
In the inter-segmental septum
How many bronchopulmonary segments does each lung have?
10
- On left: each lobe has 5
- On right: inferior has 5, middle has 2, superior has 3
Bronchopulmonary segments in the upper lobe in the right lung
- Apical
- Anterior
- Posterior
Bronchopulmonary segments in the middle lobe in the right lung
- Medial
- Lateral
Bronchopulmonary segments in the lower lobe in the right lung
- Superior or apical
- Posterior
- anterior
- Lateral
- Medial
Bronchopulmonary segments in the upper lobe in the left lung
- Apical
- Anterior
- Posterior
- Superior
- Inferior
Bronchopulmonary segments in the lower lobe in the left lung
- Superior or apical
- Posterior
- anterior
- Lateral
- Medial
Epithelium in the bronchi
• pseudostratified columnar epithelium of the bronchi
Epithelium in the bronchioles
• Simple cuboidal epithelium
Type 1 alveolar cells
Permits diffusion
Type 2 alveolar cells
Produces surfactant
What is viewed in a bronchoscopy?
- Whole of the trachea
- Main and lobar bronchi
- Commencement of the first segmental divisions can be seen
How should the carina appear in a bronchoscopy and what could it be if different?
- Sharp
- If distorted, something is growing inferior to it - tumour or enlarged lymph node
What is the significance of the apical segment of the inferior lobe?
- Inferolateral to the upper, posterior portion of the oblique fissure
- Its tertiary bronchus drops off the bronchial tree posteriorly and is prone to pneumonia
- Especially in bed ridden patients (gravity)
What is the arterial supply of the lung tissue?
- Bronchial arteries
- 1 on the right from the 3rd posterior intercostal artery or the superior posterior Intercostal artery
- 2 on the left from the aorta
What may bronchial arteries anastomose with and where?
- Pulmonary arteries
- in the walls of the bronchioles
What is venous blood drained by?
- Bronchial veins (into the azygos system)
- Or by pulmonary veins
What is the function of the Pulmonary arteries
• Carry deoxygenated blood to the lungs at a low pressure
Describe the position of the right pulmonary artery
- Passes anterior to the right pulmonary bronchus and posterior to the ascending aorta and Superior vena cava
- The left pulmonary artery is shorter
What is the primary lymph drainage and what do they drain to?
- Deep lymphatic plexus and superficial lymphatic plexus
- Drains to the pulmonary nodes buried in the hilum
Where is the deep lymphatic plexus?
Runs alongside the arteries and dividing bronchial tree
Describe the lymph drainage from the pulmonary nodes
- Pulmonary nodes to
- Bronchopulmonary (around the main bronchi in the hilum) to
- Inferior and superior tracheobronchial to
- Paratracheal (posterior mediastinal also drain to the paratracheal) to
- Bronchomediastinal lymph trunks (left and right) (parasternal and anterior mediastinal also drain to here)
- Thoracic duct
Red arrow
Superior tracheobronchial
Green arrow
(carinal) inferior tracheobronchial
Blue arrow
Paratracheal
Black arrow
Left and right bronchomediastinal trunk
Nerve supply to the lungs
- Supplied by pulmonary plexuses around the main bronchi at the root of the lung
- Parasympathetic from the vagus synapse in the plexuses
- postganglionic fibres: Bronchoconstrictor, vasodilator, secretomotor
• Sympathetic fibres from the sympathetic trunk synapse in the sympathetic ganglia
- postganglionic fibres: Bronchodilator, vasoconstrictor
Tumour impinging on phrenic nerve
Paralysis of the diaphragm on the affected side
Tumour impinging on the sympathetic trunk
Horners syndrome
Tumour impinging on the aorticopulmonary window
- Left recurrent laryngeal nerve injury
- Hoarseness of the voice
What is a tracheostomy?
• Surgically created air passage to help patient breath
What are the indications for a tracheostomy?
- Laryngeal obstruction: diptheria, foreign body, tumour
- Evacuation of excessive secretion
- For long lasting artificial respiration
What are the indications for a tracheostomy?
- Laryngeal obstruction: diptheria, foreign body, tumour
- Evacuation of excessive secretion
- For long lasting artificial respiration (poliomyelitis, severe chest injuries)
What are the indications for a tracheostomy?
- Laryngeal obstruction: diptheria, foreign body, tumour
- Evacuation of excessive secretion (severe postoperative chest infection in a patient too weak to cough adequately)
- For long lasting artificial respiration (poliomyelitis, severe chest injuries)
Where is an incision for a tracheostomy made?
A vertical incision is made downwards from the cricoid cartilage
• Halfway between cricoid and suprasternal notch
Why is the incision for a tracheostomy vertical?
To avoid the anterior jugular vein
What is a disadvantage of a vertical incision in a tracheostomy?
Langer’s lines are horizontal
• Scar tissue
What is an alternative to the vertical incision in tracheostomy?
Transverse skin crease incision
What would happen if the isthmus of the thyroid was hit?
It is an endocrine organ so has a huge blood supply and would bleed lots
What would happen if the isthmus of the thyroid was hit?
It is an endocrine organ so has a huge blood supply and would bleed lots
What are the two ways to treat a pneumothorax?
- Needle aspiration: 2nd-3rd intercostal space in the midclavicular line
- Catheter aspiration: 4th or 5th intercostal space at the midaxillary line
What is the red arrow?
Bronchopulmonary (around main bronchi in the hilum)
What is the green arrow?
Inferior and superior tracheobrachial
What is the blue arrow?
paratracheal
What is the red arrow?
Left recurrent laryngeal nerve
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When doing a needle aspiration for a pneumothorax, what structures does the needle pass thorugh?
- Skin
- Pectoralis major and possibly minor
- external, internal and innermost intercostal
- endothoracic fasica
- parietal pleura
