Pleurae Anatomy

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Pleurae Question And Answers

Question 1. Write a short note on pleural cavities and the types of pleura.
Answer:

Pleural Cavities

  • Pleural cavities are present on both sides of the mediastinum
  • They envelop the lungs.

Pleurae Pleural Cavity And Costomediastinal Recess In Cross-section

Pleural Cavities Extent:

  • Superiorly: Above the fist rib (4 cm above fist costal cartilage)
  • Inferiorly: Up to a level, just above the costal margin
  • Medially: Related to the mediastinum.

Read And Learn More: Thorax Anatomy

Pleura

  • Pleura are thin serous membranes
  • Pleura is formed by:
    • Mesothelium (single layer of fat cells)
    • Connective tissue
  • Pleura is divided into two, based on the location
    • Parietal Pleura: Outer layer of pleural cavity
    • Visceral Pleura (Pulmonary Pleura): Firmly attached to lung surfaces and fissures
  • The pleural cavity is actually the space between the parietal and visceral pleura
  • It is filled with a thin layer of serous fluid, this helps to reduce friction between the visceral and parietal pleura, so that the visceral pleura can freely slide over the parietal pleura.

Parietal Pleura

  • Due to its close relation with the thoracic wall
  • It is divided into four parts, based on the part of the thoracic wall to which it is related:
  1. Costal Pleura:
    • Costal Pleura lines the inner aspect of ribs and intercostal spaces and also an inner aspect of the sternum
    • The Costal Pleura is loosely attached to the corresponding surfaces through the endo thoracic fascia.
  2. Diaphragmatic Pleura:
    • The diaphragmatic Pleura covers the upper surface of the diaphragm.
  3. Mediastinal Pleura
    • Mediastinal Pleura is part of the pleura covering the mediastinum
    • Between T 5 and T 7 levels, the mediastinal pleura extends as a sleeve-like tube over the structures passing between the mediastinum and the lung (pulmonary vessels, bronchus)
    • The tubular covering of the mediastinal pleura along with the structures passing through it forms the root of the lung
    • Mediastinal pleura becomes continuous with the visceral pleura at the hilum of the lung.
  4. Cervical Pleura
    • Also known as the Dome of Pleura
    • Cervical Pleura is a dome-shaped layer
    • Cervical Pleura extends 5 cm above the first costal cartilage and 2.5 cm above the medial 1/3rd of the clavicle
    • The cervical pleura is covered superiorly by the Suprapleural membrane

Parietal Pleura Relations:

  • Anteriorly
    • Scalenus anterior muscle
    • Subclavian artery
  • Posteriorly
    • First rib
    • Cervicothoracic ganglion
    • Superior intercostal artery

Nerve Supply Of Parietal Pleura:

They are supplied by somatic afferent fibers through intercostal nerves and phrenic nerves

Costal Pleura: Intercostal nerve

Diaphragmatic pleura and mediastinal pleura: Phrenic nerve.

Parietal Pleura Applied Anatomy

  • Since the costal pleura is innervated by intercostal nerves, its pain is felt to the thoracic wall
  • Since diaphragmatic and mediastinal pleura are innervated by phrenic nerves, pain is felt on the supraclavicular region and lateral surface of the neck.

Visceral Pleura

  • Also known as pulmonary pleura
  • It is firmly attached to the surfaces and fissures of the lung
  • It is continuous with parietal pleura at the hilum
  • Nerve supply: By visceral afferent nerves, so, as a result, its pain is insensitive.

Question 2. What is the pulmonary ligament?
Answer:

Pulmonary Ligament

  • The parietal pleura runs downwards as a thin fold from the root of the lung and extends beyond the hilum up to the mediastinum, known as the pulmonary ligament
  • It contains loose areolar tissue and few lymphatics
  • It stabilizes the position of the inferior lobe and also acts as a space for pulmonary veins to expand during increased venous return.

Question 3. Write a note on pleural recess.
Answer:

Pleural Recess

  • In normal quiet respiration, the lungs do not fully occupy the anterior and inferior regions of the pleural cavity
  • These regions/spaces are called a pleural recess
  • They are spaces provided for the lungs to expand during deep inspiration

Pleurae Pleural Cavity And Costomediastinal Recess

  1. Costomediastinal Recess
    • Anterior recess, formed by costal and mediastinal pleura
    • Lies behind sternum and costal margin
    • The left costomediastinal recess is larger than the right
    • In normal quiet respiration, the right costomediastinal recess is filed, but a part of the left costomediastinal recess is free due to the presence of cardiac notch.
  2. Costodiaphragmatic Recess
    • Largest recess
    • Recess used for clinical purposes
    • Formed between costal and diaphragmatic pleura
    • Lies inferiorly
    • Extent: From 8th to 10th ribs in the mid-axillary line
    • Vertically it is about 5 cm long
    • Only gets filed during deep inspiration.
  • Pleural Recess Applied Anatomy
    • Pneumothorax: The pleural cavity sometimes gets filled with air
    • Traumatic Pneumothorax: It can be due to injury to the thoracic wall or lung, leading to leakage of air into the pleural cavity
    • Spontaneous pneumothorax: Occurs by leakage of air from the lung, resulting from rupture of cysts or lesions, it is associated with pulmonary tuberculosis.

Question 4. Write a brief on the blood supply and lymphatic drainage of the pleura.
Answer:

Parietal Pleura

1. Arterial Supply:

  • Intercostal arteries
  • Internal thoracic artery
  • Musculophrenic artery.

2. Venous Drainage: Azygos vein and internal thoracic vein.

Visceral/Pulmonary Pleura

  • Arterial supply: Bronchial arteries
  • Venous drainage: Bronchial veins.

Lymphatic Drainage Of Pleura

1. Parietal Pleura

  • Intercostal lymph nodes
  • Internal mammary lymph nodes
  • Posterior mediastinal lymph nodes
  • Diaphragmatic lymph nodes.

2. Visceral/Pulmonary Pleura:

Bronchopulmonary Lymph Nodes

Pleurae Multiple Choice Questions

Question 1. ‘Pulmonary cavity’ and ‘pleural cavity’ are different names for the same thing:

  1. True
  2. False

Answer: 2. False

Question 2. The lowest extent of the pleural cavity into which tissue does not extend is known as:

  1. Costodiaphragmatic recess
  2. Costomediastinal recess
  3. Cupola
  4. Inferior mediastinum

Answer: 1. Costodiaphragmatic recess

Question 3. At which location is the parietal pleura continuous with visceral pleura?

  1. On the surface of the mediastinum
  2. Throughout the entire pulmonary cavity
  3. At the hilum of the lungs
  4. On the diaphragm

Answer: 3. At the hilum of the lungs

Question 4. The portion of the parietal pleura that extends above the first rib is called the:

  1. Costodiaphragmatic recess
  2. Costomediastinal recess
  3. Costocervical recess
  4. Cupola

Answer: 4. Cupola

Question 5. The pleural cavity near the cardiac notch is known as the:

  1. Costodiaphragmatic recess
  2. Costomediastinal recess
  3. Cupola
  4. Hilum
  5. Pulmonary ligament

Answer: 2. Costomediastinal recess

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