Prepared by: Ali Jassim Alhashli, BSc www.alhashli.com Kingdom of Bahrain Arabian Gulf University College of Medicine and Medical Sciences Unit II – Problem 2 – Anatomy Pleura and Lungs Prepared by: Ali Jassim Alhashli, BSc www.alhashli.com

The Pleura Pleura: It is a thin serous membrane that forms a cavity on each side (pleural cavity) into which each lung sinks. Notice that the slippery surface is on the inside of this cavity. Parietal pleura: It lines the inner surface of thoracic wall and mediastinum. Notice that it is separated from thoracic wall by endothoracic fascia. It is composed of 4 parts: Costal. Diaphragmatic. Cervical (cupula: which is projecting above the first rib and reinforced by Sibson’s fascia – a thickened portion of endothoracic fascia). Mediastinal.

The Pleura

The Pleura Parietal pleura (continued): Innervation: Notice that parietal pleura is very sensitive to pain. It is innervated by: intercostal nerves + phrenic nerves. Arterial blood supply: Superior phrenic artery. Superior intercostal artery. Posterior intercostal artery. Internal thoracic artery. Parietal pleura forms what is known as pulmonary ligaments (although they are NOT truly ligaments) which extend from hilum of each lung to its base (its diaphragmatic surface). This provides a dead space for vein expansion or descending of lung roots. The Pleura

The Pleura Visceral pleura: It is covering the surface of the lung. Visceral pleura is insensitive to pain but sensitive to stretch (by vasomotor and sensory endings of the vagus nerve). Vasculature: Arterial blood supply: bronchial arteries. Venous drainage: bronchial veins (into the azygos venous system). Pleural cavity: It is a potential space between parietal and visceral pleurae (a closed sac with no continuation between right and left parts). It contains serous fluid which decreases friction between the two parts of the pleura. It forms to recesses: Costo-diaphragmatic recess: costal parietal pleura in contact with diaphragmatic parietal pleura. It allows lung to expand during inspiration. In case of pleural effusion, it accumulates fluid in the erect position. Costo-mediastinal recess: costal parietal pleura in contact with mediastinal parietal pleura. The Pleura

The Pleura Pleural reflection: Lower border of the pleura: on both sides crosses the: 8th rib: mid-clavicular line. 10th rib: mid-axillary line. 12th rib: vertebral column. Lower border of the lungs: 6th rib: mid-clavicular line. 8th rib: mid-axillary line. 10th rib: vertebral column. The Pleura

The Pleura Pleural effusion: Accumulation of excess fluid in pleural cavity. There are 2 types of fluid: Transudate: clear watery fluid caused by congestive heart failure. Exudate: cloudy viscous fluid caused by: tuberculosis, pneumonia, lung cancer and inflammation. Clinical signs: Decreased breath sounds. Dullness to percussion. Decreased chest expansion. Treatment: Thoracocentesis: aspiration of fluid by placing a needle in 9th intercostal space at mid-axillary line. Pay attention to insert the needle at the upper border of ICS to avoid damage to neurovascular bundle.

The Pleura Tension pneumothorax: It occurs when air goes in but does not leave pleural cavity. Therefore, air gets accumulated and pressure rises. This results in: Depressed diaphragm. Mediastinal shift (tracheal deviation). Increased heart rate. Decreased blood pressure due to decreased venous return (resulting in distended jugular veins). The Pleura

Respiratory System

Respiratory System

Respiratory System Pneumocytes (cells of the lung): Type-I cells (97%): Squamous and thin for optimal gas diffusion. Lining the alveoli. Type-II cells: Cuboidal and clustered. Secrete pulmonary surfactant which: Decreases alveolar surface tension. Prevents alveolar collapse (atelectasis) which occurs most on expiration. Composed of: dipalmitoylphosphatidylcholine. Serve as stem cells for themselves and for type-I cells. Clara cells: Low columnar/cuboidal cells, non-ciliated with secretory granules. Functions: Secrete components of surfactant. Degrade toxins. Act as reserve cells.

Respiratory System

Relations of the trachea Respiratory System Relations of the trachea

Respiratory System

Respiratory System Heimlich Maneuver Applied With Aspiration of Foreign Body

Respiratory System Heimlich Maneuver Applied With Aspiration of Foreign Body

Respiratory System Lungs: Vasculature: Arterial blood supply: bronchial arteries. Venous drainage: Bronchial veins: draining large sub-divisions. Pulmonary veins: draining small sub-divisions. Innervation: Parasympathetic (vagus nerve): for bronchoconstriction and secretomotor. Sympathetic (T1-T5): for bronchodilation and vasoconstrictor. Base of both lungs rests on the diaphragm and descends with inspiration. Respiratory System

Respiratory System Right lung: It is composed of 3 lobes: superior, middle and inferior. It has a higher risk to be obstructed by foreign bodies: If aspiration of foreign body occurs in upright position: lower portion of right inferior lobe gets obstructed. If aspiration of foreign body occurs in supine position: upper portion of right inferior lobe gets obstructed. It is larger, heavier but shorter and wider than the left lung. It has 2 fissures: Oblique fissure: which begins at the head of 5th rib and follows the line of the 6th rib. Horizontal fissure: which begins at the level of 6th rib in mid-axillary line to 4th costal cartilage. It has grooves for: Superior Vena Cava (SVC), esophagus and arch of azygous vein. Respiratory System

Respiratory System Left lung: It has 2 lobes: Superior lobe. Inferior lobe. + a lingula (which is a homologue of right middle lobe). Left lung does not contain a middle lobe because that space is occupied by the heart. It has 1 fissure: oblique fissure. It contains: Cardiac impression + cardiac notch. Grooves for: aortic arch, descending aorta and left subclavian artery. Respiratory System

Respiratory System

Respiratory System Pulmonary artery: Carries deoxygenated blood to alveoli. Passes superiorly → bifurcates in front of left main bronchus to → to right and left pulmonary arteries. Pulmonary vein: Drains oxygenated blood from alveoli to left atrium + deoxygenated blood from the visceral pleura and a part of the bronchi. Usually 4 pulmonary veins enter the left atrium. Respiratory System

Respiratory System From pulmonary nodes to bronchopulmonary nodes. Then, it will drain to superior and inferior tracheobronchial nodes. Then, it will move to left and right bronchomediastinal trunks. Left drainage is in the thoracic duct while right drainage is in the right lymph duct.