L5. Lungs and Pleura anatomy

Question 1

What are the three divisions of the Thoracic cavity and

Answer 1

Right and left hemi thorax and mediastinum = 3 sections

Question 2

What is the linings of the pulmonary cavity- pleural space, inner to outer

Answer 2

Visceral pleura adherent to the lungs and parietal pleura lines the pulmonary cavity. Endothoracic fascia adheres the parietal pleura to thoracic wall, and is continuous with fibrous Suprapleural membrane at the apex.
The pulmonary ligament is a sleeve of pleura hanging down below lung hilum

Question 3

What is the innervation of the linings of the pulmonary cavity

Answer 3

Visceral pleura: ANS from Vagus CNX and T1-4 sympathetic nerves which confer dermatome pain.

Parietal pleura: Sensitive to pain. intercostal nerve for intercostal PP, and phrenic nerve for diaphragmatic and mediastinal PP.

Question 4

Where can you find the surface markings of the pleura and lungs: 3 lines

Answer 4

Lungs: 
Midclavicular line: Rib 6
Mid axillary line: Rib 8 
Scapular line: rib 10.
Pleura is 2 ribs below each of the lungs at each line: eg. MCL=rib 8

Question 5

Where are the 2 recesses (small potential space) and how is this important

Answer 5

Between the ribs and the heart = costomediastinal recess
Between the posterior diaphragm and the base of the lung (rib 8 to 10) =costodiaphragmatic recesses.
If there is pleural effusion/ pneumothorax/ infection of the lung, it will fill up this space so need a chest drain

Question 6

Compare the lobes and fissures of the left and right lung

Answer 6

Both lungs have superior and inferior lobe separated by the oblique fissure.
Left lung also has a lingula part of the superior lobe which sits over the heart.
Right lung has extra lobe: middle which is separated from the superior by the Transverse fissure

Question 7

Describe the 4 levels of segmentation of bronchi, the 3 structures passed by the left main bronchus and the clinical implication of angle of main bronchi

Answer 7

Segments go from 0.Trachea to

1. main bronchi at the Carina (T4/5). Left main bronchus crosses pulmonary trunk, oesophagus, and arch of aorta.
2. Lobar bronchi, then
3. segmental bronchi.

Right main bronchi has a more vertical angulation than left therefore more likely to inhale objects which introduce bacteria-> leading to pneumonia

Question 8

Define a bronchopulmonary segment

Answer 8

Smallest functionally independent region of the lung. With a segmental bronchus, branch of pulmonary artery and branch of the bronchial artery. There are 10 segments per lung separated by thin CT allowing for surgical resection. Veins and lymphatics drain along edges of the segments.

Question 9

What is the orientation of structures at the pulmonary hila

Answer 9

Bronchus is the most posterior structure with cartilage and smooth inner muscular wall.
Pulmonary arteries are the most superior vessels with pulmonary veins being the most inferior/ anterior.

Question 10

What are the ANS and somatic nerve supplies and what pain do they refer for

Answer 10

ANS: make the ant and post. pulmonary plexuses, containing Vagus CNX and Symp T1/2-4 ganglia. This refers a chest pain to the T2-4 dermatomes for visceral pleura/lung pain.

Somatic nerves:
Intercostal nerves innervate intercostal muscles and give specific localised pain for chest wall puncture through the body wall and parietal pleura.

Phrenic nerve (C3-5) innervates the diaphragm and refers diaphragmatic and parietal pleura pain to the shoulder dermatome.

Question 11

Describe the path of lymphatic drainage of the lung

Answer 11

1. Pulmonary nodes
2. Bronchopulmonary (hilar) nodes
3. Inferior tracheobronchial (carinal) nodes
4. Paratracheal nodes
5. Right lymphatic duct entering R venous angle OR Thoracic duct (entering L venous angle).

Question 12

What is the blood supply and drainage of the lungs

Answer 12

Bronchial arteries supply blood: 2 to the L lung and 1 to the R lung.
Bronchial veins drain deoxygenated blood back to the azygos system however a small amount drains into the pulmonary veins carrying oxygenated blood back to the LA so it never has 100% oxygenation.

Question 13

What is the general order of blood flow through the lungs (not supplying it)

Answer 13

RA –> pulmonary trunk –> 1 pulmonary artery per lung (deoxygenated).
Gets oxygenated–> 2 pulmonary veins –> LA

Question 14

What is the impact of a patent ductus arteriosus

Answer 14

Connection between aorta and pulmonary trunk is maintained so it can increase blood flow to the lungs - pulmonary hypertension/oedema.
Decreasing blood flow to the rest of the body = organ damage
Makes the heart work harder than normal.

Question 15

What is the impact of a patent foramen ovale - if not silent

Answer 15

Can lead to lower than normal oxygen levels in the arterial blood, as well as pulmonary hypertension.

Question 16

Where is the best place to put a chest drain and what layers of the body wall does the needle go through

Answer 16

Needle needs to go anterior or posterior to the mid axillary line to avoid the long thoracic nerve.
It needs to go in the middle of the intercostal space, inferior to the edge to avoid the intercostal bundle between around rib 8-10.

Layers are skin and superficial fascia-> 3 intercostal muscles-> endothoracic fascia-> parietal pleura.