Lower Respiratory Tract Anatomy PDF

Lower Respiratory Tract Dr. Reem Busaeed  Describe the thoracic cavity and mediastinum (boundaries, organization, and content) List the parts of the lower respiratory system Describe the tracheobronchial tree, lungs, and...

Lower Respiratory Tract Dr. Reem Busaeed  Describe the thoracic cavity and mediastinum (boundaries, organization, and content) List the parts of the lower respiratory system Describe the tracheobronchial tree, lungs, and lung roots and their relations. Lecture Describe the arrangement of parietal and visceral pleura and the recesses of the pleural cavity. Objectives Identify the surface anatomy of lower respiratory tract. Describe the blood supply and innervations of lower respiratory tract and pleura List examples of clinically important problems of the lower respiratory tract and pleura. Pleurae Two serous membranes Surrounds the lungs and Separated by mediastinum Two layers Parietal pleura Lines ribcage & covers upper surface of diaphragm Visceral pleura Covers lungs Extends into interlobar fissures Pleural cuff Surround the hilum Pulmonary ligament Pleural cavity (space) Pleural fluid Costodiaphragmatic recess  Mediastinum Right side Left side Innervation of pleura Parital pleura Sensitive to different modalities of sensory stimuli (temperature, touch, pressure) Costal pleura – intercostal nerves Mediastinal pleura – phrenic nerve Diaphragmatic pleura Over domes – phrenic nerve Around the periphery – 7-12 intercostal nerves Visceral pleura Sensitive to stretch Autonomic innervation – pulmonary plexus Trachea Extends from cricoid cartilage to carina (C6 to T4- T5) Divides into right and left primary bronchi Length Adult (11.25 cm) Infant (5 cm) Width Adult (2.5 cm) Infant (begins by 3 mm) Increase 1mm/1 year 4 layers Mucosa Submucosa Hyaline cartilage Adventitia 16-20 C-shaped rings of hyaline cartilage Open part faces esophagus Trachealis muscle  Trachea Relations – In the neck – In the thorax Sensory nerve supply – Vagi & recurrent laryngeal nerves Blood supply – Upper ⅔ - inferior thyroid aa. – Lower ⅓ - bronchial aa. Lymphatic drainage – Pretracheal, paratracheal , & deep cervical nodes  Bronchi – Carina – internal ridge Most sensitive area for triggering cough reflex – Right and left primary (principal, or main) bronchi goes to right and left lung – Divide to form bronchial tree Secondary (lobar) bronchi (one for each lobe), tertiary (segmental) bronchi, bronchioles, terminal bronchioles – Structural changes with branching Mucous membrane changes Incomplete rings become plates and then disappear As cartilage decreases, smooth muscle increases – Sympathetic ANS – relaxation/ dilation – Parasympathetic ANS – contraction/ constriction Bronchi and Bronchioles Primary bronchi supply each lung Secondary bronchi supply each lobe of the lungs (3 right + 2 left) Tertiary bronchi supply each bronchopulmonary segment Repeated branchings called bronchioles (< 1 mm) form a bronchial tree Terminal bronchioles Respiratory bronchiole (0.5 mm) Alveolar ducts Alveolar sacs Alveoli Bronchi Right primary bronchus Wider, shorter & more vertical (25°) Length (2.5 cm) Crossed superiorly by azygos vein Gives three lobar bronchi Superior (branch before hilum) Middle Inferior Left primary bronchus More horizontal (45°) Length (5 cm) crossed superiorly by arch of aorta Gives two lobar bronchi Superior Inferior Lungs Shape - conical Apex (cupula) Base Costal surface Mediastinal surface Impression of mediastinal structures Right lung - heart, esophagus, superior and inferior vena cava, arch of azyos vein Left lung – heart, arch and descending aorta Hilum Root Bronchi – most posterior Pulmonary arteries – most superior Pulmonary veins – most inferior Anterior border Cardiac notch Lingula  Lungs: Lobes & Fissures Lobes – each lung divides by 1 or 2 fissures – Each lobe receives its own secondary (lobar) bronchus that branch into tertiary (segmental) bronchi Lobules wrapped in elastic connective tissue and contains a lymphatic vessel, arteriole, venule and branch from terminal bronchiole Terminal bronchioles branch into respiratory bronchioles which divide into alveolar ducts About 25 orders of branching Lungs: Lobes & Fissures Right lung Larger, wider & shorter Fissures Oblique fissure Horizontal fissure Lobes Upper Middle Lower Left lung Oblique fissure Upper & lower lobes Bronchopulmonary Segments Part of a lobe Functional and structural unit of the lung Shape - pyramidal Served by tertiary (segmental) bronchus, artery, lymph vessels and autonomic nerves Veins between segments Surrounded by CT Bronchopulmonary Segments Structures within a Lobule of Lung Branchings of single arteriole, venule & bronchiole are wrapped by elastic CT Respiratory bronchiole simple squamous Alveolar ducts surrounded by alveolar sacs & alveoli sac is 2 or more alveoli sharing a common opening Lungs: Blood Supply Lungs, bronchi, and visceral pleura Descending aorta → bronchial arteries → capillaries → bronchial veins → azygos & hemiazygos veins Alveoli Pulmonary artery (1) → alveolar capillaries → pulmonary veins (2) Lungs: Lymph drainage Superficial (subpleural) plexus → surface of lung → hilum of lung → bronchopulmonary nodes Deep plexus → bronchi & pulmonary vessels + pulmonary nodes → hilum → bronchopulmonary nodes Bronchopulmonary nodes → tracheobronchial nodes → bronchomediastinal lymph trunk  Lungs: Innervation Sympathetic trunk Vagus nerve Pulmonary plexus Sympathetic efferent – bronchodilatation & vasoconstriction Parasympathetic efferent – bronchoconstriction, vasodilatation, & glandular secretion Afferent fibers follow the efferent ones Surface anatomy of lungs Apex- Anterior border Right Left Cardiac notch- begins at 4th costal cartilage Lower border MC (midclavicular line)-6th rib MA (midaxillary line)- 8th rib Vertebral- 10th rib Posterior border- Surface anatomy of lungs Oblique fissure- with the course of the 6th rib Horizontal fissure- with the course of the 4th rib Surface anatomy of pleura Cervical pleura- Anterior border right Left Cardiac notch- begins at 4th costal cartilage Lower border MC-8th rib MA- 10th rib Vertebral- 12th rib Costodiaphragmatic recess- between lungs and pleura Posterior border- Lungs Lungs Hilum of lung Pleural Cavities Bronchial Tree Bronchi