Anatomy: Pleura and Lung Flashcards
What is the pleura lined by?
The pleura isa fibrous tissue lined by a single layer of squamous cells (mesothelium)
Explain the two layers of the pleura
Parietal pleura - layer lining thoracic wall (rib cage, vertebrae, and diaphragm)
Visceral pleura - also known as the pulmonary pleura / layer completely covering the lung. At the root of the lung it is continuous with mediastinal parietal pleura.
What is the pleural cavity?
The pleural cavity is a space between the visceral pleura and the parietal pleura.
Under what conditions can a potential pleuritic space become a real space?
NB: In the living body potential space and visceral pleura touches the parietal pleura. This no longer becomes potential (virtual) under pathological conditions
Pathological conditions such as:
Pneumothorax = air present in the pleural cavity
Excess fluid present in the pleural cavity resulting in compression of lungs and hence breathing difficulties, includes the following:
Pleural effusion = fluid can be serous
Haemothorax = blood in the pleural cavity resulting from trauma
What are the subdivisions of parietal pleura?
- Costal pleura
- Mediastinal pleura
- Diaphragmatic pleura
- Cervical pleura
Description.
- Costal pleura lines the inner surface of the thoracic wall
- Mediastinal pleura lines the mediastinum
- Diaphragmatic pleura lines the superior surface of the diaphragm
- Cervical pleura (cupula) extends superior to the first rib
Which type of parietal pleura is continuous with all layers?
Mediastinal pleura
How far does the cervical pleura extend into the root of the neck?
3-4cm above the level of the first costal cartilage.
Summit: 2-3cm above the medial third of the clavicle
Which tissue connects the diaphragm to the diaphragmatic pleura?
The phrenicopleural fascia
What is a pleural recess?
These are areas where parietal pleura contacts (meets) parietal pleura
What are the types of pleural recesses?
- Costomediastinal recess
2. Costodiaphragmatic recess
What is the costomediastinal recess?
There are 2 costomediastinal recesses (Left and right)
The costomediastinal recess occurs posterior to the sternum where the costal pleura meets the mediastinal pleura
It is the potential space behind the sternum and costal cartilages, where the anterior margin of the lung fails to reach the anterior margin of pleura.
What is the costodiaphragmatic recess?
There are two also (left and right) located in the most inferior limits of the parietal pleura where costal pleura meets the diaphragmatic pleura.
What is the purpose of the costomediatinal recess?
Purpose of the potential space is to assist the lung expansion during deep inspiration.
- costodiaphragmatic recess is more significant.
What are parietal folds?
These are lines of pleural reflection which can occur where COSTAL PLEURA meets DIAPHRAGMATIC PLEURA or MEDIASTINAL PLEURA
What is the extent of the costodiaphragmatic recess?
Extends from the 8th to the 10th rib along the mid-axillary line.
What is the relation the the diaphragmatic pleura and the lung?
The lower limit of the lung is about 5cm above the lower limit of the pleura
What is the endotharacic fascia?
Connective tissure between the thoracic walla and costal parietal pleura
What is the purpose of the endothoracic fascia?
Provides cleavage plane for surgical separation of pleura from thoracic wall
What is the pulmonary ligament?
It is a double layered parietal fold which extends beyound the root of the lung and hence is inferior to the root and anterior to the esophagus.
What is the arterial supply of the parietal pleura?
Supplied by the intercostal, internal thoracic and musculophrenic arteries.
Memba: Parietal pleura is near to the vertebrae and intercostal muscles so it makes sense.
What is the venous drainge of the parietal pleura?
Drains into the azygous system of veins.
What is the lymphatic drainage of the parietal pleura?
Lymph drains into the intercostal, parasternal, disphragmatic and posterior mediastinal nodes
What is the nerve supply of the parietal pleura?
The costovertebral (costal and peripheral diaphragmatic) pleura is supplied by intercostal nerves.
The mediastinal and central diaphragmatic pleura are supplied by the phrenic nerve.
What is the blood supply to the viscera?
The blood supply is by the bronchial artery
What is the venous drainage of visceral pleura?
The venous drainage is by bronchial veins ; mainly to pulmonary veins.
What is the nerve supply to the visceral pleura?
Autonomic sympathetic and parasympathetic ( T2-T5 & Vagus)
What is the lymph drainage of the visceral pleura?
Bronchopulmonary lymph nodes
What is the development of the parietal pleura?
Somatopleural layer of the lateral plate mesoderm
What is the development of the visceral pleura?
Splanchnopleural
What is the inferior border of the costodiaphragmatic recess related to?
The kidney close to the lateral border og the erector spinae at the level of the 12th rib.
Why are children more vulnerable to pneumothorax?
Trauma to the apex of lung and cervical pleura are increased in infants and young children because of the shortness of their necks.
Where injuries to the root of the neck may cause pneumothorax.
Accumulation of air in the pleural cavity which may be due to trauma applies to which condition?
A pneumothorax
What is pleural effuision?
The collection of fluid due to infection or neoplastic conditions.
Pleural effusion can cause obliteration of the costophrenic angle.
What are the types of pleural effusion?
Hydrothorax Hemothorax Chylothorax Pyothorax Urinothorax
What happens in a pleural effusion?
The mediastinum becomes displaced to the left.
The side(s) of the pleural cavity affected results in compression of the lung(s)
Auscultation results in faint breath sounds over the compressed lung and absent breath sounds over the fluid in the cavity.
What is pleuritis (pleurisy)?
Inflammation of the pleura that may be associated with sharp chest pain on exertion. This pain worsens during inspiration.
A pleural rub may be a dectectable sign for pleuritis.
Pleural adhesion may also be present due to inflammation.
On set of pain to the pleural membranes due to pleuritis is more prominent in which membrane?
Visceral pleura – insensitive to pain;
Parietal Pleura – sensitive to pain and may produce local or referred pain
How is a pneumothorax and hence callapsing of the lung brought on?
A penetrating wound through the thorax / lung results in air sucked into the pleural cavity – leading to collapse of the lung
and expansion of the pleural cavity
Treatment of a pleural effusion
Thoracentesis
Thoracentesis - involves the insertion of a needle into the pleural cavity to obtain a sample of fluid (9th ICS in the midaxillary line during expiration)
Insertion of a chest tube can be used to treat a tension pneumothorax or a large pleural effusion. Explain how.
In a tension pneumothorax (air enters the pleural cavity during inspiration but cannot escape during expiration).
With a large pleural effusion fluid builds up excessively in the parietal cavity.
They both require an insertion of a chest tube for drainage.
The incision is made in the 5th/ 6th ICS in the midaxillary line (directed upwards for air / downwards for fluid removal)
The tube is connected to an underwater drainage system with controlled suction
What are the 3 surfaces and 3 borders of the lung?
Surfaces:
Costal, mediastinal and diaphragmatic
Borders:
Anterior, posterior anf inferior.
Apex of the lung sits in the?
Cupula of the lungs
Location of cupula and apex of lung
Apex of lung and cupula of pleura lie superior tot he plane of the superior thoracic aperture and are located in the neck.
Give a description of costal surface
Costal surface is related to thoracic wall.
In preserved specimens the lungs show impressions for ribs, costal cartilages & intercostal muscles
What is the description of the diaphragmatic surface (base)
The diaphragmatic surface is concave and is deeper on the right.
The diaphragmatic surface is related to the diaphram. Inferior to the surface on the:
Right - the right lobe of the liver and;
Left: is the left lobe of liver, gastric fundus, spleen.
What is the mediastinal pleura?
Shows the hilum of the lungs and pulmonary ligament
Anterior to the hilum is the cardiac impression which is larger on the left
MEMBA: heart is mainly on the left
Explain the borders of the lung
Anterior border is thin and sharp and it overlaps the pericardium
What is the posterior border of the lung?
The posterior border is the rounded end which intervenes between the costal and mediastinal surface
What is the inferior border of the lung?
It is thin and sharp separating the diaphragmatic surface from the costal and mediastinal surfaces.
Give a description of the right lung
Has a greater volume than the left lung
Three lobes - superior, middle, and inferior
Two fissures:
Oblique/Major fissure (deep to fifth rib laterally and deep to sixth costal
cartilage anteriorly).
Horizontal fissure: deep to fourth rib and fourth costal cartilage.
Also called minor or transverse fissure
Description of the left lung
- Two lobes: superior, and inferior
- One fissure: Oblique fissure
- Cardiac notch on anterior border of superior lobe
- Lingula:on the inferior-medial portion of superior lobe (similar to middle lobe of right lung)
What are the mediastinal impressions on the right lung?
- Cardiac impression
- Esophagus impression
- Arch of azygous vein impression
- Superior vena cava impression
What are the mediastinal impressions on the let lung?
- Cardiac impression
- Aortic arch impression
- Thoracic aorta impression
What structures are present in the root of lungs?
- Pulmonary artery
- Bronchus
- Pulmonary veins
- Bronchial vessels
- Autonomic nerves
- Lymph nodes
