Lungs - Summary Gray\'s Anatomy for Students PDF

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Summary

Summaries of the Thorax chapter in the Third edition of this textbook. Page references are given....

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Lungs

167-176

Right > Left Each is a half-cone shape with a  Base on diaphragm  Apex projects above rib 1 into neck root.  2 Surfaces: Costal & Mediastinal  Borders: Inferior, Anterior & Posterior Root of the lung Short tubular collection of structures attaching lung to mediastinum Covered by mediastinal pleura reflecting on lung surface as visceral pleura. In Mediastinum N. vagus passes posterior to lung root. N Phrenic pass immediately anterior to lung root. Hilum: Region outlined by pleural reflection on medial surface Where structures enter and exit the lung Pulmonary ligament: Thin blade-like pleural fold extending inferiorly from root of lung, extends from hilum to mediastinum. - Stabilizes inferior lobe’s position - Accommodates up & down translocation of root structures during breathing. Each root has pulmonary artery (superior to Hilum), 2 pulmonary veins (inferior), a main bronchus (posterior), bronchial vessels, nerves and lymphatics Lobar bronchus differentiation Left Right branches from main bronchus branches to superior lobe from within the lung itself main bronchus in root of lung

Right Lung 1

o 3 lobes: superior, middle and inferior o 2 fissures: oblique, horizontal Oblique Separates inferior lobe from both superior & middle lobes Approximate position during quiet respiration, crosses SP TIV, fifth interspace laterally and follows rib VI anteriorly. Horizontal Separates superior and middle lobes Follows fourth intercostal space from sternum until it meets oblique fissure as it crosses Rib V. Lobes contact: o Superior lobe: Upper part antlat wall & apex of lobe projects into root of the neck. Right Subclavian a and v arch over lobe as they pass into axilla. o Middle lobe: Adjacent to lower anterior & lateral wall o Inferior lobe: Costal surface in contact with posterior & inferior walls. Medial surface adjacent to mediastinal structures: Heart, IVC, SVC, Azygos vein, Esophagus. -------------------------------------------------------------------------------------------------------Left Lung o 2 lobes: superior and inferior o 1 fissure: oblique Oblique Separates 2 lobes Slightly more oblique than R lung Approximate position during quiet respiration begins at SP TIII & TIV, crosses fifth interspace laterally & contours rib VI anteriorly. Lobes contact Superior: upper part antlat wall; apex extends into root of neck Left Subclavian a & v. arch over & related to this lobe as they pass into the axilla Inferior (costal surface): posterior and inferior walls Inferior portion of medial surface is notched due to hearts projection into left pleural cavity. Lingula (only of left lung) projects over the heart bulge, on ant border of lower part of superior lobe. Medial surface in contact with: Heart, Aortic arch, Thoracic Aorta, Oesophagus,

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Bronchial tree Trachea  CVI to TIV/V (bifurcation)  C-shaped cartilaginous rings, open part posterior.  Lowest tracheal ring = hook-shaped = Carina; projects backwards in midline between 2 main bronchial origins.  Posterior wall mainly smooth muscle R Main bronchus - wider - more vertical course through root & hilum (then L Main bronchus) - inhaled foreign objects more frequently lodged here than in Left. Main bronchus divides in lung into 1. Lobar bronchi (secondary bronchi): each supplies a lobe 2. Segmental bronchi (tertiary bronchi): supply bronchopulmonary segments (BPS) - Within each BPS, segmental bronchi branch and eventually bronchioles are present which also subdivide to supply respiratory surfaces. - Walls of bronchi held open by discontinuous elongated cartilaginous, not present in bronchioles. Bronchopulmonary segments Smallest independent functional unit of a lung pyramidal shaped smallest subdivision of a lobe surgically resectable separated by connective tissue septa supplied independently by segmental bronchus & tertiary branch of pulmonary artery/drained by tertiary vein.  18-20

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Superior lobes

Middle lobes Inferior lobes

Right Apical Posterior Anterior Lateral Medial Apical Medial basal Anterior basal Lateral basal Posterior basal

Left Apical Posterior Anterior Superior Inferior Medial basal Anterior basal Lateral basal Posterior basal

Pulmonary vessels 3

R & L pulmonary aa. (from pulmonary trunk) & carry deoxygenated blood from right ventricle of heart. Bifurcation of pulmonary trunk @ level just inferior to TIV/TV, antero-inferior to left of trachea bifurcation. R pulmonary artery - is longer than left - passes horizontally across mediastinum - anteroinferior to tracheal bifurcation & ant to R main bronchus - posterior to ascending aorta, SVC & Upper right pulmonary vein L pulmonary artery - shorter than right - anterior to descending aorta - posterior to Superior pulmonary vein - passes through root & hilum and branches within lung Pulmonary veins Each side: Superior and Inferior pulmonary vv. carry oxygenated blood to the heart. Begin at Hilum, pass through root of lung, and straight into left atrium.

Bronchial vessels Arteries Nutritive vascular system of lungs A right bronchial artery arises from 3rd posterior intercostal artery/ upper left bronchial artery (occasionally). Two left bronchial arteries arise directly from thoracic aorta’s anterior surface - superior left bronchial artery arises at TV - inferior left bronchial artery arises inferior the left bronchus Run on posterior surface of the bronchi & ramify in the lungs to supply tissue. Veins Bronchial vv. either drain into - pulmonary vv. - left atrium - azygos vein on R - hemi-azygos/superior intercostal vein on L

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Innervation Lung structures & visceral pleura = visceral afferents and efferents (anterior pulmonary and posterior pulmonary plexus). The plexuses lie ant & post to tracheal bifurcation and main bronchi. Anterior plexus < Posterior plexus - branches of the plexuses originate from the sympathetic trunk & Vagus nerve, and are distributed along branches of the airway & vessels. Visceral efferents from  Vagus: constrict bronchioles  Sympathetic system: dilate bronchioles Lymphatic drainage Tracheobronchial lymph nodes Superficial (subpleural) & deep lymph nodes

Found along roots of lobar & main bronchi & side of trachea. Extend from within lung through hilum and root to posterior medisatinum

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