Session 2 - The pleura Flashcards
What is the pleura?
• A serous membrane consisting of a single layer of mesothelial cells with a thin layer of underlying connective tissue
What is the parietal pleura?
• Lines the inside of the hemithorax and becomes continuous at the hilum of the lung with the visceral pleura.
What does the visceral pleura line?
• Extends between the lobes of the lung into the depths of the oblique and horizontal fissures
What is the blood supply of the pleura?
• The intercostal and internal thoracic arteries and veins
What is the innervation of the pleura?
• Both somatic (intercostal and phrenic nerves) and autonomic
What is pleural space?
• A potential space between two layers of pleura which are continuous at the hilum
What is the purpose of pleural fluid?
• Allows the two layers of the pleura to slide over one another with minimal friction.
What is the blood and nerve supply to the parietal pleura?
- The intercostal arteries and internal thoracic arteries
* Somatic innervation from phrenic and intercostal nerves
What is the blood and nerve supply to the visceral pleura?
- Bronchial arteries and drained by the bronchial veins
* Only autonomic innervation
What is the pleural cavity?
• A potential space between two layers of pleura that are continuous at the hilum
What does the pleura fluid allow?
• Two layers to slide on one another
What are the lines of pleural reflection?
• The lines along which the parietal pleura change direction
Give three lines of pleural reflection
- Sternal
- Costal
- Diaphragmatic
Where does the trachea commence?
• At the lower border of the cricoid cartilage in the neck
What is the angle between the right and left main bronchi known as?
The carina
How is the trachea held open?
• By 18-22 C shaped cartilages
Supported posteriorly by trachealis muscle
What is the angle between the right and left main bronchi known as?
• Carina
What is the cell type which lines the trachea?
Pseudo stratified columnar ciliated epithelium
Which bronchus is wider, shorted and more vertical than the other?
• The right
What do the primary bronchi divide into?
• Lobar bronchi
What is the part of the lung supplied by each segmental bronchus called?
Bronchopulmonary segment
Describe a bronchopulmonary segment
• A pyramid shaped area of lung with its apex facing towards the hilum and base towards lung surface.
Each is supplied by a segmental branch of the pulmonary artery and pulmonary vein
Why is knowledge of bronchopulmonary segments surgically important?
• Because they can be isolated and removed without much bleeding or air leakage, or intefering with other bronchopulmonary segments
What can be visualised with a bronchoscopy?
• The whole inner trachea, the carina, the main bronchi, lobar bronchi and the origin of the segmental bronchi can be visualised
Can be used to see bronchial carcinomas
What do bronchial arteries supply?
• Supply the bronchi from Carina to the respiratory bronchioles, visceral pleura and connective tissue
Outline the arterial supply of the thorax
- Thoracic aorta -> 2x left bronchial
* Thoracic aorta -> 3rd intercostal -> 1xRight Bronchial
Outline the pulmonary circulation of the lungs
• Pulmonary trunk -> Pulmonary -> Lobar -> Segmental
Outline pulmonary drainage of the lungs
- Two pulmonary veins on each side
* Middle lobe vein is a major tributary of the right superior pulmonary vein
What do the superficial group of bronchial veins drain into on the left?
• Drain visceral pleura and bronchi in the hilar region to the accessory hemiazygous vein
What do the superficial group of bronchial veins drain into on the right?
Drain visceral pleura and bronchi in the hilar region to the azygous vein
What do the deep bronchial veins drain and into what do they do this?
• Deep bronchi into main pulmonary vein or directly into left atrium
probable impossible
What do the parietal pleura line?
• The costal, diaphragm and mediastinal surfaces of each hemi thorax
What is a line of pleural reflection?
• Relatively abrupt lines along which the parietal pleura changes direction from the costal surface to the diaphragmatic surface and mediastinal surface
Where does the apex of the pleural cavity and lung extend?
About 3cm above the medial part of the clavicle
What can you deduce if a patient presents with a harmless looking bulge in the supra-clavicular fossa?
• The supra pleural membrane which prevents the lungs and pleura bulging into the neck is not present
Where do the anterior borders of the pleural cavitys descend to?
• Behind the sternoclavicular joint to reach the midline at the level of the sternal angle
Describe the pat of the right pleural cavity
• Descends vertically to reach the 6th costal cartilage
• Then loops round, crossing
○ The 8th rib at the midclavicular line
○ The 10th rib at the midaxillary line
○ The 12th rib in the back (scapular line)
○ Then ascends vertically with the paravertebral muscles
Describe the path of the left pleural cavity
• Deviates to the edge of the sternum, then descends vertically to reach the 6th costal cartilage
• Then loops round, crossing
○ The 8th rib at the midclavicular line
○ The 10th rib at the midaxillary line
○ The 12th rib in the back (scapular line)
○ Then ascends vertically with the paravertebral muscles
Where do the lungs not fill the pleura?
- The lower margins
* In front of the heart
How much higher is the lower margin of the lung than the lower margin of the pleura?
Two ribs higher
Describe the path of the lungs
- Crosses 6th rib at the midclavicular line
- 10th rib at the midaxillary line
- 10th rib in the back
Ascends vertically with paraverterbral muscles
What does the left lung have which means it skirts the pericardium?
- Cardiac notch
- From the sternal angle, neraly reaches midclavicular line before curving round to the hearts apex in the 5th intercostal space
Where does the oblique fissure extend to and from?
- Between upper and lower lobes
* Extends from spinous proces of T2 verterbra posteriorly to the 6th costal cartilage anteriorly
Where does the horizontal fissure extend to and from in the right lung?
• Mid axillary line, anteriorly along the 4th rib to the anterior edge of the lung
Why is it important to know the extent of the lungs and pleura?
• During clinical examination of the lungs and in interpreting chest x-raus
Name three procedures which can cause pneumothorax (air in the pleural cavity)
- Exposure of the kidney
- Liver biopsy
- Insertion of a sub-clavicular canulation line into the subclavianvein
Name three organs the lower parts of the abdominal organs overlap with
- Liver
- Kidney
- Spleen
Name two structures that lie below the apices of the pleura
- Subclavian vessels an
* Brachial plexus
