SDL Worksheet - Lungs & Pleura Flashcards
Define pleura and the pleural cavity
The serous membrane investing the lungs (visceral or pulmonary pleura) and lining the walls of the thoracic cavity (parietal pleura); the two layers enclose a potential space, the pleural cavity.
Location of mediastinal pleura?
Covers the lateral aspect of the mediastinum (the central component of the thoracic cavity)
Location of cervical pleura?
Lines the extension of the pleural cavity into the neck
Location of the costal pleura?
Covers the inner aspect of the ribs, costal cartilages, and intercostal muscles.
Location of the diaphragmatic pleura?
Covers the thoracic (superior) surface of the diaphragm
What are the recesses in the pleural cavity? Why do these occur?
- Costodiaphragmatic recess 2. Costomediastinal recess Anteriorly and posteroinferiorly, the pleural cavity is not completely filled by the lungs. This gives rise to recesses – where the opposing surfaces of the parietal pleura touch.
Where is the costodiaphragmatic recess?
Located between the costal pleurae and the diaphragmatic pleura
Where is the costomediastinal recess?
Located between the costal pleurae and the mediastinal pleurae, behind the sternum.
What is the clinical importance of these recesses?
Provide a location where fluid can collect (e.g. pleural effusion)
Where does the horizontal fissure of the lung run?
Runs horizontally from the sternum, at the level of the 4th rib, to meet the oblique fissure.
What are the 3 lung surfaces?
- Mediastinal surface 2. Base of lung 3. Costal surface
Describe the mediastinal surface of the lung
Faces the lateral aspect of the middle mediastinum. The lung hilum (where structures enter and leave the lung) is located on this surface.
Describe the base of the lung
Formed by the diaphragmatic surface. It rests on the dome of the diaphragm, and has a concave shape. This concavity is deeper in the right lung, due to the higher position of the right dome overlying the liver.
Describe the costal surface of the lung
The costal surface is smooth and convex. It faces the internal surface of the chest wall. It is related to the costal pleura, which separates it from the ribs and innermost intercostal muscles.
Where are the nerves of the lungs derived from? What do they feature?
Derived from the pulmonary plexuses. They feature sympathetic, parasympathetic and visceral afferent fibres
Where are the parasympathetic fibres of the nerves of the lungs derived from? What do they stimulate?
Derived from the vagus nerve. They stimulate secretion from the bronchial glands, contraction of the bronchial smooth muscle, and vasodilation of the pulmonary vessels.
Where are the sympathetic fibres of the nerves of the lungs derived from? What do they stimulate?
Derived from the sympathetic trunks. They stimulate relaxation of the bronchial smooth muscle, and vasoconstriction of the pulmonary vessels.
What is the function of the visceral afferent fibres of the nerves of the lungs?
Conduct pain impulses to the sensory ganglion of the vagus nerve.
What does the right bronchial vein drain into?
The azygos vein
What does the left bronchial vein drain into?
The accessory hemiazygos vein.
Describe X-ray during expiration
- Lungs airless and density increased - Raised diaphragm leads to exaggeration of heart size and obscuration of lung bases
What is the pleural sac?
A balloon like structure which encloses the lung. There are two, one on either side of the mediastinum.
What is the mediastinum?
A space between the pleural sacs which contains the heart and great vessels (and others)
What are the attachments of the visceral pleura?
The surfaces of the lung
What is represented by potential space A and C?
A - Pleural cavity C - Costodiaphragmatic recess
Point B indicates the boundary between which two subdivisions of the parietal pleura?
Diaphragmatic and costal
What is the function significance of the pleural recesses?
Allows the smooth expansion of the lungs during inspiration
What would be the consequences of a stab injury to the neck if it hit the apex/pleural cavity?
The lung would collapse as the atmospheric pressure would force air into the thoracic cavity.
What is haemothorax?
Blood in pleural cavity
What is chylothorax?
An accumulation of lymphatic fluid in the pleural space. Lymph formed in the digestive system is called chyle and accumulates in the pleural space due to either disruption or obstruction of the thoracic duct.
What is empyema?
A collection of pus in the pleural cavity. Usually associated with pneumonia but may also develop after thoracic surgery or thoracic trauma.
Abnormal substances within the pleural cavity may be removed by means of a chest drain. Where is a non-emergency chest drain usually inserted?
5th intercostal space, mid-axillary line.
What is the visceral pleura innervated by?
Autonomic innervation from the pulmonary plexus (vagus nerve and sympathetic fibres). It is insensitive to pain stimuli (sensory receptors only detect stretch)
What is the parietal pleura innervated by?
Innervated by the intercostal nerves, with the mediastinal and diaphragmatic pleura also innervated by the phrenic nerve
Irritation of the parietal pleura can produce referred pain where?
In the thoracic and abdominal walls (intercostal nerves)
Left lung root:
Pulmonary artery above bronchus RALS
Right lung root:
2 pulmonary arteries: both anterior to the bronchus (looks like next to) RALS
What structures pass through the root of the lung?
Pulmonary arteries, pulmonary veins, bronchi, bronchial arteries, autonomic nerves, lymph nodes and vessels
Where do the bronchial arteries arise? What do they supply?
Paired vessels from the aorta They supply the bronchi and lung tissue.
Where do lymphatic vessels from the lung substance drain to?
Hilar lymph nodes in the lung root which in turn drain to nodes around the bifurcation of the trachea (tracheo-bronchial nodes)
What can enEnlargement of the nodes due to infection or carcinoma lead to?
Obstruction of bronchus
What is effect of obstruction of a bronchus on the lung?
Deflation of the lung distal to the blockage
Compare the right primary bronchus to the left
The right primary bronchus is wider, shorter and more vertical than the left. This accounts for the greater tendency of foreign bodies (e.g. peanuts, an extracted tooth) and aspirated material (e.g vomit) to enter the right bronchus rather than the left.
X-ray of thoracic cavity
