Chapter 3. Lungs | The Big Picture: Gross Anatomy | AccessPharmacy | McGraw-Hill Medical
The visceral pleura is contiguous with the parietal pleura at the site where The recess where the costal parietal pleura meets the diaphragmatic parietal pleura. Pleura: Pleura, membrane lining the thoracic cavity (parietal pleura) and covering the lungs (visceral pleura). The parietal pleura folds back on itself at the root of. The pleurae refer to the serous membranes that line the lungs and thoracic cavity . They permit efficient and effortless respiration. This article will outline the.
The pleura is a serous membrane which folds back onto itself to form a two-layered membrane structure. The thin space is known as the pleural cavity and contains a small amount of pleural fluid few milliliters in a normal human. The outer pleura is attached to the chest wall 1 - 9. The pleural cavity aids optimal functioning of the lugs during breathing.
It transmits movements of the chest wall to the lungs, particularly during heavy breathing. The closely approved chest wall transmits pressures to the visceral pleural surface and hence to the lung 10 - In human, there is no anatomical connection between the pleural cavities.
The visceral pleura receives its blood supply from the bronchial circulation and the parietal pleura receives its blood supply from the intercostal arteries. Only in cases of pneumonothorax tension-simultaneous may collapse the contralateral parenchyma and blood vessels.
Normally visceral pleura glides on parietal without sound or pain, but when the pleura are in action sounds can be auscultated. If fluid then distends cavity, the sounds disappear and the lung gradually the heart and mediastinum being displaced towards the lung.
Air the cavity, rupture of the lung as the elastic tissue of the lung recoils. The pleura crosses the rib at the region is above the reflexion.
The thoracic structures inlet consist of two groups. Those in the median plane and those on each side closely related to the cervical parts of pleurae and lungs. The thoracic outlet is wider transversely and slopes down, so the vertical extend of the cavity is longer. The diaphragm closes the opening and forms a convex floor for the cavity. Centrally, it is flatter. The diaphragm slopes down to the costal and vertebral attachments, so the thoracic wall narrows rapidly inferiorly 29 - The thoracic cavity is divided by the mediastinum.
The heart is in the mediastinum, enclosed by the pericardium. The lungs occupy the left-right regions and the pleura lines the corresponding half of the thorax and forms the lateral mediastinal boundary.
The superior part extends from the thoracic inlet passing through the lower edge of manubrium sterni. The inferior part is subdivided into an anterior part of the pericardium.
The pericardium contains the heart and juxtacardiac parts. It is posterior to corpus sterni and anterior to the thoracic vertebrae. It consists of two opposed surfaces of serous membrane fibrous pericardium-serous pericardium. The fibrous pericardium is compacted of collagenous fibrous tissue. The serous pericardium is a thin layer of flat mesothelial cells which blends with the fibrous pericardium and myocardial tissue.
The mediastinum is the partition between the lungs and includes the mediastinal pleura.
It is commonly applied to the internal between the two pleural sacs, the sternum and the thoracic vertebral column extending to the diaphragm. The superior mediastinum is lying between the manubrium sterni and the upper four thoracic vertebrae. It contains the ends of the sternohyoid, colli muscles, left common carotid, the brachiocephalic artery and the aortic arch 3239 - The anterior mediastinum lying between the sternal body and pericardium.
It contains loose areolar tissue, the sternopericardial ligaments, sometimes part of thymous gland and the mediastinal branches of the internal thoracic artery. The middle mediastinum contains pericardium, ascending aorta, the terminal azygos vein, both pulmonary veins, the phrenic nerves and tracheal bifurcation.
The posterior mediastinum is bounded in front by the tracheal bifurcation, pericardium and the upper surface of diaphragm, behind by the vertebral column.
It contains the thoracic aorta, the vagus, the azygos-hemiazygos vein and the thoracic duct. Each lung is invested by a delicate serous membrane and the pleura, which is arranged in the investigated sac. A portion of the serous membrane dips into the fissures between its lobes—the pulmonary pleura. The rest of the membrane lines cover the diaphragm—the parietal pleura. The two layers are continuous with one another around and below the root of the lung—the pleural cavity. The right and left pleural sacs are entirely separate and they touch each other for a short distance in front, opposite the 2nd-3rd pieces of the sternum the interval between the two sacs—the mediastinum.
In the front of the chest, where the parietal pleura is reflected backward to the pericardium, the two pleural sacs are in contact. At the upper part of the chest they are separated by an angular interval. From this point the two pleurae descend in close contact to the level of the fourth costal cartilages. The inferior limit of the pleura is on a considerably lower level than the corresponding limit of the lung but does not extend to the attachment of the diaphragm.
Between the two layers of pleura forms—the costomediastinal sinus. The line along which the right pleura is reflected from the chess-wall to the diaphragm starts in front and runs behind the seventh costal cartilage. The right sac is shorter, wider and reaches higher in the neck Figures 1 - Figure 1 Anatomy of the respiratory system.
Figure 2 Anatomy of the respiratory system within the thorax region. Figure 3 Anatomy of the pleura cavity. Figure 4 Two pleural layers continue with each other at root of the lung forming a closed potential cavity: Figure 5 Anatomy of the pleura cavity mechanism detail.
What is the structure, function, and location of the pleura, pericardium, and peritoneum?
Figure 6 Anatomy of the pleura cavity muscles. Figure 7 Anatomy of the pleura cavity pleural layers. Figure 8 Anatomy of the pleura cavity respiratory system. Figure 9 The parietal pleura lines the thoracic wall and superior surface of the diaphragm. It continues around the heart forming the lateral walls of the mediastinum. The pleura extends over the surface of the lungs as the visceral pleura. Rarely, the azygos vein, instead of arching over the hilus of the right lung, arches over the upper lobe so that it isolates a medial part of the lung, called the lobule of the azygos vein.
The anterior border of the lung corresponds to that of the pleura, although it is uncertain whether the costomediastinal recess of the pleura is completely filled by the lung during quiet breathing, as it is in deep inspiration. The anterior border of the left lung probably deviates more to the left cardiac notch than does that of the pleura. The portion of the upper lobe of the left lung that lies between the cardiac notch and the oblique fissure is known as the lingula, and it corresponds to the middle lobe of the right lung.
The inferior border of the lung occupies the costodiaphragmatic recess of the pleura, although it is too thin to be demonstrated by percussion during quiet breathing. The liver, stomach, spleen, colon, kidney, and peritoneal cavity extend to a higher level than the periphery of the diaphragm and the inferior border of the lung.
Hence any perforation of the lower intercostal spaces should be considered an abdominal as well as a thoracic wound.
The inferior limit of the lung that can be outlined by percussion extends laterally from the xiphisternal joint and about two intercostal spaces higher than the pleura.
It crosses rib 6 in the midclavicular line and rib 8 in the midaxillary line and then proceeds toward the 10th thorac vertebra. Considerable individual variation occurs, however. Lobes and fissures see fig. The left lung is divided into upper and lower lobes by an oblique fissure. The oblique fissure follows approximately the line of rib 6 as far as the inferior border of the lung.
When the arm is abducted and the hand placed on the back of the head, the medial border of the scapula indicates approximately the oblique fissure. The horizontal fissure begins at the oblique fissure near the midaxillary line of the right sideat about the level of rib 6. It extends forward to the anterior border at the level of costal cartilage 4. It may be incomplete or even absent. It connects the medial surface of each lung to the heart and trachea. It is surrounded by pleura, which is prolonged below as the pulmonary ligament.
The roots of the lungs descend on deep inspiration. The chief structures in the root are the bronchi and pulmonary vessels.Pleura - Pleural Cavity (anatomy)
Also included are nerves, bronchial vessels, and lymphatics and nodes. The heart and great vessels are anterior to the trachea and main bronchi, and this relationship is maintained in the root of the lung, where the anterior-posterior order, is veins, artery, and bronchus, with the artery superior to the veins. The portion of lung supplied by a third-order bronchus is known as a bronchopulmonary segment. A given segment may be located by radiography or bronchoscopy.
Pulmonary disorders may be localized in a bronchopulmonary segment, and surgical removal of a segment is feasible. The segments are separated from each other by connective tissue septa. Although variations are not uncommon, the bronchopulmonary segments have been named and numbered fig.
The Pleurae - Visceral - Parietal - TeachMeAnatomy
There are slight differences between the right and left lungs: The branches of the pulmonary artery accompany the bronchi but are more variable. Pulmonary veins do not accompany the bronchi, but run between the segments; hence they are guides to intersegmental planes.
Blood supply, lymphatic drainage and innervation Blood to be oxygenated is carried by the pulmonary arteries, whereas the tissue of the bronchial tree and alveoli is nourished by the bronchial arteries.
The branches of the pulmonary arteries within the lungs accompany the bronchi and end in capillary networks in the alveoli. The arteries at the hilus are visible radiographically and form a pattern that extends into the lung.
The pulmonary veins collect oxygenated blood from the lung and deoxygenated blood from the bronchi and visceral pleura.
Pulmonary veins are intersegmental in location. Usually four pulmonary veins enter the left atrium.
Chapter The pleurae and lungs
Bronchial arteries, usually one on the right and two on the left, arise commonly from the aorta, but variations are frequent. They supply oxygenated blood to the non-respiratory tissues of the lungs, including the visceral pleura.
Bronchial veins carry deoxygenated blood from the first few bronchial divisions to the azygos system. Carbon particles in the superficial lymphatics give the lung a grayish and mottled appearance.
Superficial and deep lymphatic vessels drain toward the hilus and end in pulmonary and bronchopulmonary nodes. These in turn drain into the tracheobronchial nodes.
The anterior and posterior pulmonary plexuses around the root of the lung are formed by branches of the vagi and sympathetic trunks. Parasympathetic fibers of vagal origin supply the smooth muscle and glands of the bronchial tree. Spasm of the bronchial musculature occurs in asthma and can be relieved by epinephrine.
Sympathetic fibers supply blood vessels and probably relax bronchial smooth muscle. Afferent fibers vagal from the visceral pleura and bronchi are concerned with the reflex control of respiration. Irritation of endings in the bronchial mucosa provokes coughing.
Physical and radiological examinations The classic methods of physical examination are inspection, palpation, percussion, and auscultation.
Corresponding areas on the two sides of the chest should be compared systematically. Inspection includes examination of the scapulae, clavicles, ribs, sternal angle, subcostal angle, expansion of the chest, and movement of the abdominal wall.
The rate of respiration is normally 11 to 14 per minute, i. It is higher in children, and the neonatal rate is two to three times as high as the adult rate. Palpation involves feeling the trachea and also the vibrations "vocal fremitus" of the chest wall.
Percussion produces "resonance" over air-containing organs such as the lungs and "dullness" over solid organs. Auscultation ofthe breath sounds is undertaken with a stethoscope. The chief x-ray methods used in the examination of the chest are plain films and CT scans.
Bronchoscopy is used to examine the air passages and to biopsy masses and pulmonary function tests evaluate the movement of air. The most frequently employed view in radiography of the chest is the "PA" view, i. Other views are indicated in figure The bronchi and pulmonary tissue are radiolucent, but the branches of the pulmonary arteries form a visible pattern. The dense hilar shadows are produced by a combination of vascular, bronchial, lymphatic, and connective tissue components.
The bronchial tree can be outlined by a contrast medium injected by way of an intratracheal catheter introduced through the mouth or nose.
This procedure is termed bronchography fig. This has largerly been replaced by fiber-optic bronchoscopy which directly visualizes the passages. Additional reading Boyden, E. A classic on the patterns of the segmental bronchi and related pulmonary vessels. The first edition is available in English The Human Lung. A mine of pulmonary information. Questions What are the serous membranes? The serous membranes are the pleura, pericardium, and peritoneum. The tunica vaginalis testis is a usually detached extension of the peritoneum.
Serous membranes consist of mesothelium and connective tissue, and they secrete a film of serous exudate. Air may enter from the lung e. The lung then collapses. The stethoscope was invented for auscultation by Laennec in Figure legends Figure Thorax of an adult. Note the clavicles, ribs, diaphragm, cardiovascular shadow including the right atrium, aortic knuckle, and left ventricletrachea, and lungs including vascular markings.
Large descending branches of the pulmonary arteries are visible on each side of the heart.