The pleural cavities, lungs and percardium Flashcards
What is the inferior mediastinum divided into?
The anterior, middle and posterior mediastinum
Where is the anterior mediastinum located?
Between the sternum and anterior body of the pericardial sac
What does the anterior mediastinum contain?
A few lymph nodes and the thymus gland in childhood
What is contained in the middle mediastinum
The pericardium and heart, roots of the great vessels, and the hilum of each lung
What is contained in the posterior mediastinum?
The oesophagus with the vagus nerves, descending thoracic aorta, azygos vein, and thoracic duct
What is the structure of the pleura?
Pleural cavity between visceral and parietal layers
What does the visceral layer of the pleura cover?
The lung
What does the parietal layer of the pleura cover?
The inner surface of the thoracic wall, the upper surface of the diaphragm, and the sides of the pericardium
Where do the visceral and parietal layers of the pleura become continuous with each other?
At the lung hila
What is the importance of the pleural cavities?
The mechanisms of respiration are dependent upon two sealed pleural cavities
What is found within the pleural cavity?
A small amount of serous fluid
Where is the costodiaphragmatic recess?
Between the parietal pleura lining the superior diaphragmatic surface and the parietal pleura lining the thoracic wall
When is the costodiaphragmatic recess deepest?
During full expiration
What is the difference in the appearance of the 2 plural cavities?
The left pleural cavity is smaller as the heart extends further to the left
Which pleural layer is insensitive?
Visceral
How is the parietal pleura innervated?
Receives segmental innervation from intercostal nerves and the phrenic nerves, which supply mediastinal and diaphragmatic parietal pleurae
How many lobes and fissures are in the right lung?
Three lobes (upper, middle, and lower) and two fissures: the oblique and transverse (or horizontal) fissures.
What is the difference between the size and shape of the lungs?
The left is smaller and narrower
How many lobes and fissures are in the left lung?
2 lobes (upper and lower) and 1 fissure (oblique)
What is the lingula?
a small tongue of upper lobe of the left lung between the fissure and the cardiac notch; it corresponds to the middle lobe of the right lung
Where is the apex of the lungs?
2.5cm above medial third of clavicle
What is observed at the 2nd costal cartilage concerning the surface markings of the pleurae?
Pleurae from both sides meet
What is observed at the 4th costal cartilage concerning the surface markings of the pleurae?
Left diverges to accommodate the heart
What is observed at the 6th costal cartilage concerning the surface markings of the pleurae?
Right descends to this point
What is observed at the 8th costal cartilage concerning the surface markings of the pleurae?
Crosses mid-clavicular line
What is observed at the 10th costal cartilage concerning the surface markings of the pleurae?
Crosses mid-axillary line
How far down does the lung extend?
Reaches just below the neck of the 12th rib posteriorly
How do the surface markings of the lungs compare with the surface markings of the pleurae?
The surface markings of the lungs coincide with those of the pleurae, except inferiorly, where they are approximately two rib spaces higher in full expiration.
Thus, the lungs lie opposite the 6th costal cartilage in the mid-clavicular line, the 8th costal cartilage in the mid-axillary line, and reach the 10th rib posteriorly on both sides
Where does the oblique fissure start and end?
Starts posteriorly next to the spine of T3, and curves downwards and forwards to end parallel with the 6th costal cartilage
What is the easiest way to find the position of the oblique fissure?
If the arm is abducted, the medial border of the scapula is roughly in the same line as the oblique fissure