Anatomy of the pleura and lungs Flashcards

1
Q

What is the embryonic origin of the pleura?

A

The intraembryonic coelom (coelomic cavity)

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2
Q

What is the pleura?

A

It is a closed sac, invaginated by the lungs from the medial aspect, which will form the visceral and parietal layers

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3
Q

What is the pulmonary ligament?

A

It is a downward extension of the pleura as a fold below the root of the lung (hilum)

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4
Q

What is the function of the pulmonary ligament?

A
  • It provides a dead space where the lung root descends with the descent of the diaphragm, and provides the capability for the expansion of the veins during exercise
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5
Q

What is the pleural cavity?

A
  • It is a closed cavity between the parietal and visceral layers, which contains a thin film of fluid “pleural fluid” that encloses the lung
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6
Q

What is meant by pleurisy?

A
  • Inflammation (lack of pleural fluid) of the pleural makes the pleural surface rough, resulting in a pleural rub, which is detectable with a stethoscope
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7
Q

What is the visceral pleura and where is it absent?

A
  • It is the inner layer of the pleura that covers the lung & lines the fissures
  • It is absent in:

1) Hilum of the lungs

2) Between the two layers of the pulmonary ligament (made only of the parietal)

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8
Q

What is the parietal pleura and what are its divisions?

A
  • It is the layer of the pleura that lines the chest wall & covers the mediastinum

It is divided into four parts:

1) Costal (cupula)

2) Cervical

3) Mediastinal

4) Diaphragmatic

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9
Q

What is the costal pleura?

A
  • AKA cupula
  • It is the part of the parietal pleura that lies the:
    1) sternum
    2) ribs
    3) costal cartilage
    4) intercostal
    5) sides of the vertebral column
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10
Q

What is the diaphragmatic pleura?

A

The part of the parietal pleura that covers the diaphragm

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11
Q

What is the cervical pleura?

A
  • The part of the parietal pleura that covers the apex of the lungs
  • It is attached anteriorly to the suprapleural membrane (which originates from the transverse process of C7 and T1)
  • The suprapleural membrane is like the diaphragm of the thracic inlet
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12
Q

What is the mediastinal pleura?

A
  • The part of the parietal pleura that covers the sides of the mediastinum
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13
Q

What is the endothoracic fascia?

A
  • A connective tissue structure deep into the intercostal spaces and ribs separating these structures from the underlying pleura
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13
Q

What are the pleural recesses

A
  • They are narrow extensions of the pleural cavity (spaces for lung expansion)
  • They are made of parietal pleura only and are filled during expansion only
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14
Q

What is the function of the pleural recesses?

A

They allow the lungs to expand during deep inspiration

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14
Q

Where are the pleural recesses found?

A

1) Costodiaphragmatic recess

2) Costomediastinal recess

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15
Q

Where is the costodiaphragmatic recess located?

A
  • AKA costophrenic angle (its absence in X-ray = pleural effusion “hydrothorax”)
  • It lies between the costal & diaphragmatic pleura along the inferior margin of the pleura
  • Most commonly where excess fluid is drained into, due to gravity
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16
Q

Where is the costomediastinal recess located?

A
  • It lies between the costal and mediastinal pleura along the anterior margin of the pleura
  • It overlies the heart
  • Lies the anterior ends of the 4th and 5th intercostal space
  • During full inspiration it becomes occupied with the lingula of the left lung
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17
Q

How do we treat the pleural effusion “hydrothorax” of the costo-diaphragmatic recess?

A

By thoracocentesis:

  • Inserting a needle into the 9th (below the lung but within the pleura) intercostal space in the mid-axillary line, during expiration to avoid the inferior border of the lung
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18
Q

Where does the lower border of the lung end?

A
  • It depends:

1) Midclavicular line (anteriorly): 6th intercostal space

2) Midaxillary line (laterally): 8th intercostal space

3) Posteriorly: 10th intercostal space

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19
Q

What are the pleural lower borders?

A

1) Midclavicular (anteriorly): 8th intercostal space

2) Midaxillary line (laterally): 10th intercostal space

3) Posteriorly: 12th intercostal space

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20
Q

What is the nerve supply of the pleura?

A

1) Visceral pleura:

  • regarded as part of the lung (the autonomic nerve accompanying the bronchial arteries)
  • Not sensitive to pain

2) Parietal pleura

  • Regarded as part of the chest wall
  • Somatic innervation and sensitive to pain
  • Innervated by both the phrenic nerve (innervates the central part of the diaphragmatic and mediastinal pleura) and intercostal nerve (innervates both the costal and peripheral part of the diaphragmatic pleura)
  • Referred pain from the abdomen is felt through the phrenic nerve or the Intercostal nerve (T1-T11)
21
Q

Describe the blood supply of the visceral pleura

A
  • It gets its blood supply from the bronchial arteries (branches of the thoracic aorta, and the pulmonary artery)
22
Q

What is the blood supply of the parietal pleura?

A
  • Supplied by the arteries of the chest wall (internal thoracic, intercostal, and musculophrenic arteries)
23
Q

What is a pneumothorax?

A

When the chest wall is penetrated (stab wound, rupture of a bullae), air will enter into the pleural cavity, making it more positive, collapsing the lungs

24
Q

What is meant by tension pneumothorax?

A
  • When air enters during inspiration but does not exit during expiration accumulating in the cavity, compressing the ipsilateral lung and pushing the mediastinum to the other side compressing the opposite lung and eventually killing the patient
25
Q

How to treat tension pneumothorax?

A
  • By removing the excess air from the pleural cavity
  • Place a chest tube through the 5th or 6th intercostal space midaxillary line (air goes up, fluid down, that is why hydrothorax = 9)
  • You must be cautious as you can injure the long thoracic nerve resulting in a winging of the scapula
26
Q

What is a lung?

A
  • It is the main organ of the respiratory system responsible for the exchange of CO2 and O2 between air and blood
  • It is found inside the pleural cavity, separated from each other by the mediastinum
  • They are conical in shape with an apex and a base, they have 2 surfaces (costal and medial), & 3 borders (anterior, posterior, & inferior)
27
Q

How do you identify if the lung is right or left?

A
  • RIGHT LUNG:

1) The right bronchus divides before entering the hilum, and thus you will see 2 separate bronchus

2) 1 pulmonary artery (appears as two as the artery bifurcates as soon as it enters) Artery always above the vein

3) 2 pulmonary veins (1 superior and 1 inferior)

4) Bronchopulmonary lymph node

5) Related to the right phrenic nerve

6) In front of the hilum, you will have the pericardial impression of the (right atrium, groove for the SVC, IVC, and the brachiocephalic vein

7) Above the hilum you will see the arch of the Azygos vein, related to SVC, behind the esophageal impression is the Azygos vein impression, one anterior impression for the trachea, right vagus nerve, one posterior vertical impression for the esophagus

28
Q

Which lung has two separate bronchus in its hilum?

A

The right lung

29
Q

Describe the hilum of the left lung

A

1) The most posterior structure is the bronchus (only one is seen)

2) The most inferior is the inferior pulmonary vein (it has two)

3) The Most superior is the pulmonary artery

  • It is related to the left atrium and left auricle

4) Above the hilum (aortic arch and left a common carotid impression)

5) Behind the hilum is a very big groove for the descending aorta

6) The left subclavian has a very prominent grove posterior to the common carotid impression

7) Behind the left subclavian there is an impression for the thoracic duct, esophagus, and left recurrent laryngeal nerve

30
Q

What are the surfaces of the lungs?

A

1) Costal surface

2) Base of the lungs

3) Medial surface

31
Q

What is the costal surface?

A

This is the surface related to the sternum, costal cartilage, ribs, intercostal muscles, and sternocostalis muscle

32
Q

Describe the structure of the base of the lungs

A
  • It has a concave lower surface that rests on the upper surface of the diaphragm
  • The diaphragm separates the base of the lungs from the right lobe of the liver and the left lobe of the liver, fundus, stomach, and spleen, the concavity is much greater in the right lung as it has the liver beneath it
33
Q

Describe the medial surface of the lungs

A

It is divided into:

1) Vertebral part:

  • Behind the hilum, related to the sides of the vertebral bodies, intervertebral discs, posterior intercostal vessels, sympathetic trunk & splanchnic nerves

2) Mediastinal part:

  • The anterior part, and it is different between the right and left lung
34
Q

Describe the mediastinal surface of the right lung

A

1) Pericardial impression

  • Wide depression in front of the hilum and the pulmonary ligament, it is related to the pericardium and right atrium

2) Impression for the IVC

  • Related to the upper part of the IVC

3) Impression for the SVC

  • In front of the upper part of the hilum, it is continuous upwards with the groove of the right brachiocephalic vein

4) Groove for the arch of the vena azygos vein

  • Above the hilum, reaching to the groove for the superior vena cava

5) Impression for the trachea and the right vagus

  • Above the hilum, lies behind the superior vena cava groove and above the arch of the azygos vein

6) Esophagus impression

  • Verticle groove behind the hilum

7) Azygos vein groove

  • Shallow groove behind the esophagus impression
  • THE RIGHT LUNG CAN BE IDENTIFIED BY THE AZYGOUS VEIN IMPRESSION
35
Q

What are the impressions found in the mediastinal surface of the left lung?

A

1) Pericardial impression:

  • A wide depression in front of the hilum and the pulmonary ligament (due to the pericardium, left ventricle, and left auricle)

2) Impression of the pulmonary trunk and thymus gland remnants

  • Lies above the pericardial impression & in front of the upper part of the hilum

3) Above the hilum: Aortic arch

4) Behind the hilum: Descending aorta

5) SUBCLAVIAN ARTERY IMPRESSION

6) Anterior to the subclavian artery is the common carotid artery impression, Posterior to the common carotid artery are the thoracic duct, esophagus, and left recurrent laryngeal nerve (related to the common carotid “just next to it”)

7) The left phrenic nerve: Passes between the grooves of the left common carotid and left subclavian

8) Narrow vertical area behind the groove of the left subclavian artery (related to the thoracic duct, & left recurrent laryngeal nerve)

9) The esophagus forms a groove in front of the descending aorta

36
Q

What is the lingula of the lung?

A
  • It is a tongue-like production in the upper lobe at the cardiac notch
  • It is found in the superior left lobe
  • Due to the building of the heart, the cardiac notch is produced on the upper lobe of the left lung
37
Q

Where are the fissures of the lungs found?

A

1) The left lung has 1 fissure (oblique) which separates the lung into two lobes

2) The right lung has 2 fissures (oblique and horizontal) separating the lungs into three lobes (upper, middle, and lower)

  • It is the horizontal fissures that separate the upper lobe to the superior and middle lobes
38
Q

Describe the anatomical distribution of the oblique fissure

A
  • Begins at the posterior border, 2.5 inches from the apex, opposite to the 3rd thoracic spine
  • It extends downwards and forwards, cutting the inferior border of the lung opposite to the 6th costochondral junction
39
Q

Describe the anatomical distribution of the horizontal fissure

A
  • Extends from the anterior border of the right lung at the 4th costal cartilage, till it connects with the oblique fissure at the midaxillary line
40
Q

What is the hilum of the lung?

A

It is the site where the structures enters or leave the lungs

41
Q

What is the root of the lung?

A

It is the structures that pass through the hilum, connecting the mediastinum to the lung

41
Q

Describe the arrangement of the structures in the root of the lungs

A

1) Most superior: Pulmonary artery

2) Most posterior: Main bronchus

3) Most anterior and inferior: The two pulmonary veins

42
Q

Describe the bronchial arteries

A
  • The bronchial artery and veins constitute the nutritive vascular system of the pulmonary tissue
  • They interconnect within the lung with the branches of the pulmonary artery and veins

1) Origination:

  • Thoracic aorta or one of its branches
  • Right Bronchial Artery: arises from the third posterior intercostal artery
  • The two left bronchial arteries: Arises directly from the anterior surface of the aorta (descending aorta)
43
Q

Describe the branches of the bronchi

A

1) Trachea

2) Main bronchus

3) Lobar bronchus

4) Segmental bronchus

  • The MLS in the right is 10 while left it is 8-9

5) Conducting bronchiole

6) Terminal bronchiole

7) Respiratory bronchiole

44
Q

Which part of the lungs can be removed and regrown easily?

A

The bronchopulmonary segment (it can be grown into a full lung)

45
Q

Describe the differentiation of the right main bronchi

A

1) Before it enters the hilum, the right principle bronchus gives off the superior and inferior lobar bronchi

2) After entering the lung the inferior lobar divides into middle and lower lobar bronchus (so total 3 lobar bronchi, superior, middle & lower)

3) They will then divide into 10 segmental bronchi:

1) Superior: into Apical, Anterior, & Posterior

2) Middle lobar: Medial and Lateral

3) Inferior lobe: Apical & 4-basal (ant, post, lateral, and medial)

46
Q

What is the bronchopulmonary segment?

A
  • Pyramid shape with its root being situated at the apex of the lung root
  • Starts from the segmental (tertiary) bronchus
  • Each bronchopulmonary segment has its own arterial supply
  • It is a functionally independent unit of a lung
  • The largest subdivision of a lobe
  • Each segment is surrounded by connective tissue containing the intersegmental veins that drains the segment
  • Each bronchopulmonary segment can be surgically removed without affecting the other segments (not necessary to remove the whole lobe)
47
Q

Where is the apical segment of the lower lobe located?

A
  • It is located within the base of the scapular spine (triangle of auscultation)
  • Very important for detecting intrapulmonary fluid
48
Q

What is meant by segmentectomy?

A
  • Removal of the affected bronchopulmonary segment, without disturbing the surround lobes/lung tissue
49
Q

What is beonchography?

A

It is a way of visualizing the outline of the trachea and bronchi, after introducing a contrast

50
Q

What is a pulmonary embolism?

A

Obstruction of blood flow in a branch of the pulmonary artery by an embolus (lung segment will have air but no perfusion)

51
Q

Why is a pulmonary infarction rare?

A

Due to the collateral circulation as it has double blood supply where the collateral channels between the bronchial and pulmonary arteries open immediately after embolic occlusion of the pulmonary artery