Dr Vohra Pleura is a Double layered membrane

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 layer Lines the thoracic wall, covers the thoracic surface of diaphragm & lateral aspect of mediastinum & extends into root of neck Visceral layer Completely covers the outer surfaces of the lungs & extends into the depth of the interlobar fissures

Pleural Cuff Two 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/space Is 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 pleura 3. Covers the thoracic surface of the diaphragm

3. Mediastinal pleura Covers & forms the lateral boundary of the mediastinum 4. Cervical pleura Also 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 3 rd 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 recesses In 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 supply Parietal Pleura is sensitive PTTP Costal pleura Intercostal nerves Mediastinal pleura Phrenic Diaphragmatic 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 1/3 rd 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 Surfaces Costal 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 Borders Anterior 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 by the 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 supply The 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 supply Pulmonary plexus composed of autonomic nerve fibers of sympathetic & parasympathetic (Vagus) both

Lymph Drainage Two sets are present Superficial Lymph vessel re not present in alveolar walls 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