Anatomy Of The Lungs

Lungs 

The lungs develop from the protrusion of the primordial foreguts, which are divided into two buds. The left and right lungs will be formed by separate buds. The fourth week of gestation is when development begins. The alveolar stage, which happens about the seventh month of pregnancy, is the last step of development. There are 20 million alveoli in the world at birth, but alveolar proliferation lasts for an additional 10 years. After ten years, the proliferation ceases, and there may be 300 million alveoli.

Lobes And Fissures

Right lung: Divided into two fissures and three lobes.x

The first fissure is horizontal/minor, dividing the superior lobe from the middle lobe, while the second fissure is oblique, separating the lower lobe from the superior and middle lobes. The lobes are superior, middle, and inferior.

Left lung: Divided into two lobes superior and inferior. 

The lung is divided into the superior and inferior lobes by a single fissure, sometimes known as an oblique fissure. The lingula, a tongue-like extension of the left lung, is located just below the cardiac notch. That is the right middle lobe's correspondence.

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Blood Supply

The descending thoracic aorta branches off into the bronchial arteries, which feed blood to the lungs. The pulmonary artery provides blood that has been deoxygenated. Segments of the lungs can be further subdivided; these segments are referred to as bronchopulmonary segments. There are ten bronchopulmonary segments in the right lung and nine in the left lung.The superior lobe of the right lung is divided into three segments: the apical, posterior, and anterior. 

There are two segments in the middle lobe: the medial and lateral segments. 

The higher-ups, medial basal, anterior basal, lateral basal, and posterior basal are the five segments that make up the lung's inferior lobe. The left lung is identical to the right, with the exception that the left lung lacks the medial basal section. 

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Bronchopulmonary Segments

A tertiary or segmental bronchus provides ventilation for the functional and structural components of the lung known as bronchopulmonary segments. Every segment of the bronchial artery and pulmonary artery has a segmental branch. A tertiary or segmental bronchus provides ventilation for each bronchial segment, and the pulmonary vein is located in the intersegmental plane.

Lymphatic Drainage Of The Lungs

 It primarily targets the lymph nodes in the mediastinal group. There are fourteen lymph node stations in total. They are separated into various zones. Station one lymph node is located in the supraclavicular zone, which is the first zone. The lymph nodes in the sternal notch, lower cervical, and supraclavicular regions make up Station 1. The lymph nodes of Station 1 are referred to as 1R on the right side and 1L on the left. 

There are two zones that comprise the superior mediastinal lymph nodes. The aortic and upper zone lymph nodes. Station two lymph nodes, which are upper paratracheal lymph nodes, are located in the upper zone. The lymph nodes of Station 2 are referred to as 2R on the right side and 2L on the left. 

The three station three lymph nodes are referred to as 3a lymph nodes when they are located anteriorly, and 3P lymph nodes when they are located posteriorly. Lower paratracheal lymph nodes make up station four lymph nodes. Either 4R or 4L can apply. The lymph nodes located between the aorta and the pulmonary artery are known as the station five lymph nodes. These are referred to as sub-aortic or aortopulmonary lymph nodes. The paraaortic lymph nodes are located at station six.

It is possible to categorize inferior mediastinal nodes into distinct zones.
Station 7, or Subcarinal LN, is included in the first zone, which is the subcarinal zone. Stations 8 and 9 are lymph nodes in the lower zone.
Paraoesophageal lymph nodes are located in station 8, and lymph nodes along the pulmonary ligament.

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Hilar Or Interlobar Zone Lymph Nodes

Station 10 lymph nodes, which can be 10R or 10L, are located at the hilum.  The interlobar lymph nodes of Station 11 can be either 11R or 11L.  Peripheral lymph nodes, or station 12, constitute the final zone.  The lobar lymph nodes are these. segmental LN, or station 13 lymph nodes, are located on the segmental bronchi.  Subsegmental LN, or station 14 lymph nodes, are located on the subsegmental bronchi. 

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Lymphatic Sump Of Borrie

The lymphatic sump of Borrie is an interlobar lymph node located in an interlobar fissure on each side. It gets its name from the fact that all pulmonary lobes on the corresponding side send lymphatic drainage to it.
They are located between the middle and upper lobes of the bronchus on the right side, or along the bronchus intermedius. They are situated between the lower lobe bronchus and the lingular on the left side. 

Hope you found this blog helpful for your Cardiothoracic and Vascular Surgery preparation. For more informative and interesting posts like these, keep reading PrepLadder’s blogs.