Pleura and Lungs

The pleura is divided into two major types, based on location:

1. Parietal pleura2. Visceral pleura

Each pleural cavity is the potential space enclosed between the visceral and parietal pleurae.

Pleura

1. Costal part2. Diaphragmatic part3. Mediastinal part4. Cervical part

Parietal pleura

Costal pleura- Lining internal surface of thoracic wall

Mediastinal pleura- Covering sides of mediastinum

Diaphragmatic pleura- Covering superior surface of dome of each hemidiaphragm

Cervical pleura- A dome of pleura extending superiorly into superior thoracic aperture

Parietal pleura has 4 parts

Covers the lungs Cannot be dissected from lungInsensitive to pain

Visceral pleura

The parietal pleura is sensitive to pain, temperature, touch, and pressure and is supplied as follows:

The costal pleura is segmentally supplied by the intercostal nerves.

The mediastinal pleura is supplied by the phrenic nerve.

The diaphragmatic pleura is supplied over the domes by the phrenic nerve and around the periphery intercostal nerves.

Nerve Supply of the Pleura

The visceral pleura covering the lungs is sensitive to stretch but is insensitive to common sensations such as pain and touch. It receives an autonomic nerve supply from the pulmonary plexus .

visceral pleura

1. Costomediastinal recesses

2. Costodiaphragmatic recesses

Pleural recesses

Lines of Pleural Reflection

Costomediastinal recesses

Costodiaphragmaticrecesses

Excess fluid that accumulates in pleural cavity

Can impair breathing by limiting the expansion of lungs during inhalation

TypesSerous fluid (hydrothorax) Blood (hemothorax) Chyle (chylothorax) Pus (pyothorax or empyema)

Pleural effusion

Pneumothorax, Hydrothorax, and Hemothorax

Pleural effusion Chest x ray(PA View)

At least 300 ml of fluid must be present before upright chest films can pick up signs of pleural effusion 

To obtain a sample of pleural fluid or to remove blood or pus or air

To avoid damage to intercostal nerve and vessels, needle is inserted superior to rib, high enough to avoid collateral branches

It is performed at Mid-Axillary Line, one or two intercostal spaces below the fluid level but not below the ninth intercostal space.

The ideal site is eighth, or ninth intercostal space, and this site avoids possible accidental puncture of the lung, liver, spleen, and diaphragm.

Thoracocentesis

Thoracentesis

Lungs

The right lung is normally a little larger than the left lung because the middle mediastinum, containing the heart, bulges more to the left than to the right.

Each lung has a half-cone shape, with a base, apex, two surfaces and three borders.

1. Base2. Apex3. The two surfaces: Costal surface, mediastinal

surface 4. Three borders: Inferior border , Anterior and

Posterior borders

Lungs

1.Pulmonary artery

2. Two pulmonary veins

3. Main bronchus 4. Bronchial

vessels5. Nerves and

lymphatics.

Hilum of the lung

The right lung has three lobes and two fissures.

Fissures1. Oblique fissure2. Horizontal fissure

Right lung

Anatomy of the right lung displaying its two main fissures the horizontal and the oblique

1. Heart 2.Inferior vena

cava 3.Superior vena

cava 4.Azygos vein 5.Esophagus

Medial surface of the right lung

The left lung is smaller than the right lung and has two lobes separated by an oblique fissure.

On the anterior surface of the lower part of the superior lobe a tongue-like extension (the lingula of left lung) projects over the heart bulge.

Left lung

Anatomy of the left lung displaying its fissure that separates it into two lobes upper and lower lobes

1.Heart 2.Aortic arch 3.Thoracic

aorta4. Esophagus

Medial surface of the left lung

Trachea and Bronchi

Trachiobronchial Tree

TracheaBronchi

Right and left [primary]Lobar [secondary] [3 or 2]Segmental [Tertiary] [10]

BronchioleTerminalRespiratory

AlveoliAlveolar ductAlveolar SacAlveoli

Trachea bifurcates→ two main stem bronchi, right and leftCarina- keel-like ridge between two openings

of main stem bronchiMain stem bronchus divides into lobar

bronchi3 lobar bronchi on right: upper, middle, and

lower 2 lobar bronchi on left: upper and lower

Each lobar bronchus branches into segmental bronchi that supply a bronchopulmonary segment

Bifurcation of the trachea

The bifurcation of the trachea as seen through an operating bronchoscope

Aspiration of Foreign BodiesIf food, liquids, or foreign bodies are aspirated,

they often will lodge in the right mainstem bronchus.

Because right bronchus is wider and shorter and runs more vertically than left bronchus

Encountered by dentists Aspiration of piece of tooth, filling

material, or a small instrument.If the endotracheal tube used for 

intubation is inserted too far, it usually lodges in the right mainstem bronchus. This allows ventilation of the right lung, but leaves the left lung useless.

2 sets of Blood Supply

1.Pulmonary Vessels: for Gas Exchange

2. Bronchial Vessels: for blood supply to lung substance like any other organ

Vasculature of lungs

Pulmonary arteryCarries unoxygenated blood from heart to lungsEach artery gives lobar and segmental arteries

Pulmonary veins Intrasegmental veins drain to intersegmental veins

in pulmonary septa, which drain to two pulmonary veins for each lung

Carry oxygenated blood from lungs to heart

Pulmonary Vessels

Bronchial arteries Basically supply lung

substance From thoracic aorta Carry oxygenated blood

to tissue of lungs, traveling along posterior surface of bronchi

Left bronchial arteries- arise from thoracic aorta

Right bronchial artery- arise from 3rd posterior intercostal A.

Bronchial arteries

Bronchial veins

Drain to azygos and accessory hemiazygos veins