Dr. Vohra

Pleura is a Double layered membrane that invests both lungs, lies on either side of the mediastinum within the chest cavity

Consists of:Parietal layerLines the thoracic wall, covers the thoracic surface of diaphragm & lateral aspect of mediastinum & extends into root of neck Visceral layerCompletely covers the outer surfaces of the lungs & extends into the depth of the interlobar fissures

Pleural CuffTwo layers continuous with one another at the hilum (structure leaving & entering the lungs) of the lungs

Pulmonary Ligament To allow the movement of pulmonary vessels & bronchi during respiration the pleural cuff hangs down as a loose fold

Pleural cavity/spaceIs a slitlike space between parietal & visceral layers of pleura

Pleural fluid To allow the movement of pulmonary vessels & bronchi during respiration the pleural cuff hangs down as a loose fold

Is divided into:1. Costal pleura

Lines the inner surfaces of the ribs, costal cartilages, intercostal spaces, sides of the vertebral bodies & back of sternum

2. Diaphragmatic pleuraCovers the thoracic surface of the diaphragm

3. Mediastinal pleuraCovers & forms the lateral boundary of the mediastinum

4. Cervical pleuraAlso called as pleural cupula/dome Extends up into the neck, lining the undersurface of the suprapleural membrane. It reaches a level about 1 to 1 ½ inches above the medial 3rd of clavicle

Each lung has a hilum on its medial aspect. The hilum of the lung is the point of entry for the root of the lung, which includes the bronchi, the pulmonary arteries, and the pulmonary veins. A pleural sleeve is created around these structures, where the pleura reflects, changing from visceral to parietal

Inferior to the hilum on each lung is the pulmonary ligament, a continuation of that pleural reflection.

Costodiaphragmatic recessesIn quite respiration the costal & diaphragmatic pleurae are in opposition to each other below the lower border Of the lung. In deep respiration the margins of the base of the lung descend, & both pleurae separate. This lower area is called as Costodiaphragmatic recesses

Costomediastinal recesses Situated along the anterior margin of the pleura. A slitlike space b/w the costal & mediastinal parietal pleura that are separated by a capillary layer of pleural fluid

Nerve supplyParietal Pleurais sensitive PTTPCostal pleura Intercostal nerves Mediastinal pleura PhrenicDiaphragmatic pleura Domes by phrenic & around the periphery by the lower 6 intercostal nerves

Visceral Pleura The visceral pleura receives an autonomic supply from the pulmonary plexus it is sensitive to stretch but insensitive to PTTP

Soft, spongy & elastic structure in thoracic cavity. If the thoracic cavity were opened the lungs would immediately shrink to 1/3rd or less in volume

In child it is pink in but becomes darker with the age because of the inhalation of dust particles

Lie on each side of the mediastinum

Each lung is conical covered with visceral pleura & suspended free in its own pleural cavity

External Features

Each lung has a blunt apex Concave base sits on diaphragm

SurfacesCostal surface correspond to the chest Mediastinal surface

In the middle is a hilum (a depression) in which the bronchi, vessels & nerves that forms the root enter & leave the lung

BordersAnterior border of left lung is thin & overlaps the heart, it

shows cardiac notch Posterior border is thick rounded & lies beside the vertebral column

Lobes & Fissures

Right Lung

Is slightly larger than the left & is divide bythe oblique & horizontal fissure into 3 lobes the upper, middle& lower lobes

Left lung Divided by similar oblique fissure into 2 upper & lower lobes

Cardiac notch

Blood supplyThe bronchi, CT of the lung & visceral pleura is supplied by bronchial arteries branches of thoracic aorta

The bronchial vein drain into the azygos & hemiazygos veins

Two pulmonary veins leave each lung root to empty into the left atrium

Nerve supplyPulmonary plexus composed of autonomic nerve fibers of sympathetic & parasympathetic (Vagus) both

Lymph Drainage Two sets are present

Superficial Drains the surface of the lungs

Deep Drains bronchial tree, pulmonary vessels & CT. Lymph drain into bronchomediastinal trunk & finally to thoracic duct, right lymphatic duct or brachiocephalic veins

Lymph vessel re not present in alveolar walls