Thoracic Cavity and Pleurae
What is pulmonary ligament? What is its function?
Pulmonary Ligament Definition: The mediastinal pleura of parietal pleura forms a bilaminar fold known as pulmonary ligament.
Pulmonary Ligament Functions
1. It provides a dead space for the expansion of pulmonary veins in venous return. This occurs in exercise.
2. The lung roots also can expand during descent of the diaphragm.
Read And Learn More: Anatomy Important Question And Answers
Table of Contents
Enumerate Recesses of Pleura
Enumerate Recesses of Pleura Definition: These are ‘reserve spaces’ of the lung for the expansion of lung during deep inspiration. They are two in number
1. The costomediastinal recess
- Costomediastinal Situation: Anteriorly
- Costomediastinal Position: Between the costal and mediastinal pleurae.
2. The Costodiaphragmatic Recess
- Costodiaphragmatic Recess Situation: Inferiorly
- Costodiaphragmatic Recess Extent: 8th to 10th ribs along the mid-axillary line.
Give applied anatomy of pleura and pleural cavity.
1. Pleuritis: Inflammation of pleurae is known as pleurisy or pleuritis. It may be dry or wet pleurisy. Wet pleurisy is called pleural effusion.
2. Thoracocentesis: It is the tapping of the fluid from the pleural cavity. It is performed in 8th intercostal space posterior to mid-axillary line. The needle is passed through the lower part of the intercostal space to avoid injury to the intercostal vessels and nerve.
3. Pneumothorax: Presence of the air in the pleural cavity.
4. Hemothorax: Presence of blood in the pleural cavity.
5. Hydropneumothorax: Presence of both fluid and air in the pleural cavity.
6. Empyema: Presence of pus in pleural cavity.
7. Irritation of mediastinal and central part of diaphragmatic pleurae causes referred pain to the tip of shoulders. This is because of same segmental innervation.
Nerve Supply of Pleura
1. Parietal Pleura: Somatic nerves hence it is pain sensitive .
- Intercostal and
- Phrenic nerves–C3, C4 and C5
2. Costal and peripheral parts of the diaphragmatic pleurae are supplied by the intercostal nerves.
3. Mediastinal pleura, and
4. Central part of the diaphragmatic pleurae by the phrenic nerves (C4).
5. Pulmonary pleura: Autonomic nerves.
- Sympathetic nerves: 2nd to 5th ganglia, and
- Parasympathetic nerves: Vagus nerve.
- This part of the pleura is not sensitive to pain.
Costodiaphragmatic Recess
It is most dependent part of Pleural Cavity. They are one on each side.
Definition: They are slit-like spaces present between the costal and diaphragmatic parietal pleurae. They are separated only by a capillary layer of pleural fluid.
1. During inspiration, the lower margins of the lungs descend into the recesses. But costodiaphragmatic recess is not totally occupied by the lungs.
2. During expiration, the lower margins of the lungs ascend so that the costal and diaphragmatic pleurae come together again.
3. Site: Along the costodiaphragmatic lines of pleural reflection.
4. Relations
- Superiorly: Costal and diaphragmatic pleurae
- Relations of right recess
- Liver, and
- Posterior surface of right kidney
- Relations of left recess
- Fundus of the stomach,
- Spleen,
- Posterior surface of the left, and
- Left kidney.
- When the patient is in the upright position, intrapleural fluid accumulates in the costodiaphragmatic recess.
- Thoracocentesis is done for the fluid drainage. The direction of the tube is inferiorly (toward the costodiaphragmatic recess).
Applied anatomy
- Paracentesis (Gr. pierce). It is a surgical puncture of a cavity with a needle. It is also called pleurocentesis or thoracocentesis.
- Widening of costadiaphragmatic recess is the first indication of fluid in the pleural cavity.
- Inferior margin of pleura is in close relation to the12th rib. While approaching kidney from back, care should be taken to remove a section of the 12th rib.
- The presence of 300 ml of fluid in the costodiaphragmatic recess in an adult is sufficient to diagnose pleural effusion.
Parietal Pleura under Following Heads
1. Subdivisions of the Pleura, and
2. Applied Anatomy.
Subdivisions of the Pleura Introduction: It is outer covering of the lung.
1. Subdivisions of the pleura: Depending upon the structure it lines, it is called
- Costal,
- Diaphragmatic,
- Cervical, and
- Mediastinal.
Costal Pleura: It lines the inner surface of the sternum, costal cartilage, ribs, intercostal spaces and sides of vertebral bodies but the costal layer is separated by end thoracic fascia. Tracing
- It can be traced from back of the sternum-mediastinal pleura sternoclavicular joint> middle of the sternal angle >vertically up to the 4th costal cartilage.
- On the right side: It reflects vertically behind the xiphisternal joint-right costoxiphoid angle-7th costal cartilage – costodiaphragmatic line of pleura.
- On the left side: It descends close to sternum-and deviates laterally from the sternum to 4th costal cartilage costodiaphragmatic line.
- Behind: It continues with mediastinal pleura by the side of vertebral column along a line known as the costovertebral reflection.
- Above: It continues as cervical pleura along the inner border of 1st rib. d. Below: It continues as the diaphragmatic pleura.
Diaphragmatic pleura: It covers the thoracic surface of the corresponding part of diaphragm. Laterally, it continues as the costal pleura. Medially, it continues as mediastinal pleura.
Cervical Pleura: It extends from the inner border of 1st rib to the apex of the lung. It continues medially with mediastinal pleura. The summit of the cervical pleura is 3 to 4 cm above 1st costal cartilage. It does not extend above upper border of neck of 1st rib.
Mediastinal Pleura: It forms the lateral boundary of the mediastinum and is divided into three parts
- Above the root of the lung: It extends from the sternum to vertebral column.
- At the root of the lung: The mediastinal pleura passes laterally in the form of a tube enclosing the structures of the root of lung. It continues with pulmonary pleura.
- Below the root of the lung: The mediastinal pleura forms a bilaminar fold known as pulmonary ligament which extends from
- Oesophagus to corresponding lung below its hilum. At the hilum, the two layers are continuous with pulmonary pleura.
- Contents of pulmonary ligament: No important structures pass except
- Loose areolar tissue,
- Lymphatics, and
- Sometimes accessory bronchial artery.
2. Applied anatomy
Pleuritis: Inflammation of pleurae is known as pleurisy or pleuritis. It may be dry or wet pleurisy. Wet pleurisy is called pleural effusion.
Thoracocentesis: It is the tapping of the fluid from the pleural cavity. It is performed in 8th intercostal space posterior to mid-axillary line. The needle is passed through the lower part of the intercostal space to avoid injury to the intercostal vessels and nerve.
Pneumothorax: Presence of the air in the pleural cavity.
Hemothorax: Presence of blood in the pleural cavity.
Hydropneumothorax: Presence of both fluid and air in the pleural cavity.
Empyema: Presence of pus in pleural cavity.
Irritation of mediastinal and central part of diaphragmatic pleurae causes referred pain to the tip of shoulders. This is because of same segmental innervation.
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