Pleura and Lungs

Pleura The pleura is divided into two major types, based on location: 1. Parietal pleura 2. Visceral pleura Each pleural cavity is the potential space enclosed between the visceral and parietal pleurae.

Parietal pleura 1. Costal part 2. Diaphragmatic part 3. Mediastinal part 4. Cervical part

Parietal pleura has 4 parts 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

Visceral pleura Covers the lungs Cannot be dissected from lung Insensitive to pain

Nerve Supply of the 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.

visceral 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 .

Pleural recesses 1. Costomediastinal recesses 2. Costodiaphragmatic recesses

Lines of Pleural Reflection Costomediastinal recesses Costodiaphragmatic recesses

Pleural effusion Excess fluid that accumulates in pleural cavity Can impair breathing by limiting the expansion of lungs during inhalation Types Serous fluid (hydrothorax) Blood (hemothorax) Chyle (chylothorax) Pus (pyothorax or empyema)

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 

Thoracocentesis 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.

Thoracentesis

Lungs

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. Base 2. Apex 3. The two surfaces: Costal surface, mediastinal surface 4. Three borders: Inferior border , Anterior and Posterior borders

Hilum of the lung 1.Pulmonary artery 2. Two pulmonary veins 3. Main bronchus 4. Bronchial vessels 5. Nerves and lymphatics.

Right lung The right lung has three lobes and two fissures. Fissures 1. Oblique fissure 2. Horizontal fissure

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

Medial surface of the right lung 1. Heart 2.Inferior vena cava 3.Superior vena cava 4.Azygos vein 5.Esophagus

Left 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.

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

Medial surface of the left lung 1.Heart 2.Aortic arch 3.Thoracic aorta 4. Esophagus

Trachea and Bronchi

Trachiobronchial Tree Trachea Bronchi Right and left [primary] Lobar [secondary] [3 or 2] Segmental [Tertiary] [10] Bronchiole Terminal Respiratory Alveoli Alveolar duct Alveolar Sac

Bifurcation of the trachea Trachea bifurcates→ two main stem bronchi, right and left Carina- keel-like ridge between two openings of main stem bronchi Main stem bronchus divides into lobar bronchi 3 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

The bifurcation of the trachea as seen through an operating bronchoscope

Aspiration of Foreign Bodies If 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.

Vasculature of lungs 2 sets of Blood Supply 1.Pulmonary Vessels: for Gas Exchange 2. Bronchial Vessels: for blood supply to lung substance like any other organ

Pulmonary Vessels Pulmonary artery Pulmonary veins Carries unoxygenated blood from heart to lungs Each 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

Bronchial arteries 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 veins Drain to azygos and accessory hemiazygos veins