Trachea is a mobile cartilaginous and membranous tube. This fibroelastic tube is kept patent by 16 20 U- or C- shaped bars of hyaline cartilage embedded in its wall. The posterior free ends of this cartilage are connected by smooth muscle, the trachealis muscle. In adults: trachea is about 11.25 cm long & 2.5 cm in diameter. It begins: in the neck as a continuation of the larynx at the lower border of the cricoid cartilage at level of the 6th cervical vertebra. It descends in the midline of the neck. The trachea ends below at the carina by dividing into Rt. & Lt. principal (main) bronchi at the level of the sternal angle. In expiration: Bifurcation rises by one vertebral level. In deep inspiration: it may be lowered as far as T6 vertebra. 2
posterior anterior 3
Anteriorly: Sternum, thymus, Lt. brachiocephalic vein, origins of brachiocephalic & Lt. common carotid arteries & the arch of aorta. Posteriorly: Esophagus & Lt recurrent laryngeal N. Right side: Azygos vein, Rt. Vagus nerve & Rt. Pleura. Left side: Arch of aorta, Lt. common carotid, Lt. subclavian arteries, Lt. pleura, Lt. vagus & Lt. phrenic nerves. 4
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1. Arterial supply: Upper two thirds: are supplied by the inferior thyroid arteries. Lower third: is supplied by the bronchial arteries. 2. Venous drainage: Rt. Side: Azygos vein. Lt. Side: Hemiazyos vein. Also a little via bronchial and pulmonary veins. 3. Nerve supply: Branches from vagus nerve & recurrent laryngeal nerve. Sympathetic nerves supply trachealis muscle and mucus membrane. 4. Lymph drainage of the trachea The lymph drains into the pretracheal and paratracheal lymph nodes and the deep cervical nodes. 12
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The trachea bifurcates behind the arch of the aorta into Rt. & Lt. principal (primary or main) bronchi. The bronchi then divide dichotomously, giving rise to millions of terminal bronchioles that terminate in 1 or 2 respiratory bronchioles. Each respiratory bronchiole divides into 2 to 11 alveolar ducts that enter the alveolar sacs. The alveoli arise from the walls of the sacs as diverticula. 14
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Rt. Main bronchus Wider, shorter (2.5 cm long). More vertical. Before entering the hilum of the right lung, the principal bronchus gives off the superior lobar bronchus. On entering the hilum, it divides into a middle and an inferior lobar bronchi. Lt. Main bronchus Narrower, longer (5 cm long). More horizontal. It passes to the left below the arch of the aorta and in front of the esophagus. On entering the hilum of the left lung, the principal bronchus divides into a superior and an inferior lobar bronchi. 17
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During life, lungs are soft, spongy and very elastic. If the thoracic cavity were opened, the lungs would immediately shrink to one third or less in volume. In the child, they are pink, but with age, they become dark and mottled because of inhalation of dust particles (trapped in the lung phagocytes) especially seen in city dwellers, smokers and coal miners. Each lung is conical, covered with visceral pleura, and suspended free in its own pleural cavity, being attached to the mediastinum only by its root. 19
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Each lung has: 1. A blunt apex projecting upward into the neck for about 2.5 cm above the clavicle. 2. A concave base that sits on the diaphragm. 3. A convex costal surface, which corresponds to the concave chest wall. 4. A concave mediastinal surface, which is molded to the pericardium and other mediastinal structures. In the middle of this surface is the hilum, a depression from which the bronchi, vessels, and nerves that form the lung root enter and leave the lung. 5. The anterior border is thin and overlaps the heart; it is here on the left lung that the cardiac notch is found. 6. The posterior border is thick and lies beside the vertebral column. 21
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Right Lung: Right lung is slightly larger than the left. It is divided by oblique & horizontal fissures into upper, middle, & lower lobes. The oblique fissure runs from the inferior border upward and backward across the medial and costal surfaces until it cuts the posterior border about 6.25 cm below the apex. The horizontal fissure runs horizontally across the costal surface at the level of the 4 th costal cartilage to meet the oblique fissure in the midaxillary line. The middle lobe is thus a small triangular lobe bounded by the horizontal and oblique fissures. 24
Left Lung: It is divided by a similar oblique fissure into upper & lower lobes (Superior & Inf. lobes). No horizontal fissure in the left lung. 25
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Rt. lung 4 th costal cart. Midaxillary line Lt. lung 2.5 in. 27
The root of the lung is formed by structures that are entering or leaving the lung including the bronchi, pulmonary artery and veins, lymph vessels, bronchial vessels, and nerves. The root is surrounded by a tubular sheath (Cuff) of pleura, which joins the mediastinal parietal pleura to the visceral pleura covering the lungs. 28
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Definition: The bronchopulmonary segments are the anatomic, functional, and surgical units of the lungs. Each lobar (secondary) bronchus, passes to a lung lobe, & gives off branches called segmental (tertiary) bronchi. Each segmental bronchus passes to a structurally and functionally independent unit of a lung lobe called a bronchopulmonary segment, which is surrounded by connective tissue. 33
The segmental bronchus is accompanied by a pulmonary artery branch, but the tributaries of the pulmonary veins run in the connective tissue between adjacent bronchopulmonary segments. Each segment has its own lymphatic and autonomic nerve supply. 34
On entering a bronchopulmonary segment, each segmental bronchus divides repeatedly. As the bronchi become smaller, the U-shaped bars of cartilage found in the trachea are gradually replaced by irregular plates of cartilage, which become smaller and fewer in number. Smallest bronchi divide & give rise to bronchioles ( 1 mm in diameter). Bronchioles possess no cartilage in their walls and are lined with columnar ciliated epithelium. The submucosa possesses a complete layer of circularly arranged smooth muscle fibers. 35
The bronchioles then divide and give rise to terminal bronchioles, which are the last part of the conducting portion of the respiratory system. Each terminal bronchiole gives rise to several generations of respiratory bronchioles, characterized by scattered, thin-walled outpocketings (alveoli) that extend from their lumens. Gaseous exchange between blood and air takes place in the walls of these alveoli, which explains the name respiratory bronchiole. The diameter of a respiratory bronchiole is about 0.5 mm. 36
The respiratory bronchioles end by branching into alveolar ducts, which lead into tubular passages with numerous thin-walled outpouchings called alveolar sacs. The alveolar sacs consist of several alveoli opening into a single chamber. Each alveolus is surrounded by a rich network of blood capillaries. Gaseous exchange takes place between the air in the alveolar lumen through the alveolar wall into the blood within the surrounding capillaries. 37
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1. It is a subdivision of a lung lobe. 2. It is a pyramidal-shaped structure. 3. It s apex is pointing towards the root of lung. 4. It is surrounded by connective tissue. 5. It has: segmental bronchus, artery, lymph vessel & autonomic nerves. 6. The vein lies in the connective tissue between adjacent segments. 7. Because it is a structural unit, A diseased segment can be removed surgically. 40
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Rt. Lung Superior Lobe: 1. Apical. 2. Posterior. 3. Anterior. Middle Lobe: 1. Lateral. 2. Medial. Inferior Lobe: 1. Apical. 2. Medial basal. 3. Anterior basal. 4. Lateral basal. 5. Posterior basal. Lt. Lung Superior Lobe: 1. Apico-posterior. (*) 2. Anterior. 3. Superior lingular. 4. Inferior lingular. Inferior Lobe: 1. Superior. 2. Antero-medial basal. (*) 3. Lateral basal. 4. Inferior basal. 44
1. The bronchial arteries, which are branches of the descending aorta or one of its branches, supply the bronchi, the connective tissue of the lung, and the visceral pleura. A single right bronchial artery normally arises from the Rt. third posterior intercostal artery (but occasionally, it originates from the upper left bronchial artery). Two left bronchial arteries (superior & inferior) arise directly from the thoracic aorta. 2. The bronchial veins (which communicate with the pulmonary veins) drain into the azygos and hemiazygos veins. 45
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The alveoli receive deoxygenated blood from the terminal branches of the pulmonary arteries. The oxygenated blood leaving the alveolar capillaries drains into the tributaries of the pulmonary veins, which follow the intersegmental connective tissue septa to the lung root. Two pulmonary veins leave each lung root to empty into the left atrium of the heart. 49
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Subpleural (superficial) plexus drains the lung surface toward the hilum into bronchopulmonary nodes. Deep lymphatic plexus travels along pulmonary vessels toward the hilum passing through pulmonary nodes. From the hilum it drains into tracheobronchial and broncho-mediastinal nodes. 51
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At the root of each lung is a pulmonary plexus composed of efferent & afferent autonomic nerve fibers. The plexus is formed from: 1. Branches of the sympathetic trunk. 2. Parasympathetic fibers from the vagus nerve. 54
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It can be compressed by: 1. Enlarged thyroid gland. 2. Aortic arch aneurysm. 3. Double aortic arch. 56
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Inflammation of these structures (Trachea or Bronchus) causes pain deep to the sternum. N.B: Mucosa of trachea is supplied by recurrent laryngeal nerve. Mucosa of bronchi is supplied by pulmonary plexus. 58
It is common especially in children. Loose tooth can slip to the trachea in anesthetized patient. F.B tends to enter the right bronchus more than the left. It may lodge in the larynx causing asphyxia which may necessitates emergency tracheostomy. 59
Allows examination of: 1. The trachea. 2. Carina. 3. Main bronchi. 4. Even the lobar bronchi. Allows biopsy. Allows removal of F.B. 60
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TE Fistula: is an opening between the trachea and esophagus. If the margins of the laryngotracheal groove fail to fuse adequately, an abnormal opening may be left between the laryngotracheal tube and the esophagus. 62
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Atresia: is a congenital condition (birth defect) which affects the alimentary tract. It causes the esophagus to end in a blind-ended pouch rather than connecting normally to the stomach. Obstruction of the esophagus prevents the child from swallowing saliva and milk, and this leads to aspiration into the larynx and trachea, which usually results in pneumonia. Diagnosis can be made by insertion of NG tube and x- ray. The child presents with drooling of saliva, recurrent aspirations. With early diagnosis, it is often possible to correct this serious anomaly surgically. 64
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Respiratory cycle consists of 2 phases (inspiration & expiration) which are accomplished by the alternate increase and decrease of the capacity of the thoracic cavity. RR is 16 20 /min (Resting), faster in children & slower in old. Inspiration: 1. Quiet Inspiration. Compare the thoracic cavity to a box with a single entrance at the top, which is a tube called the trachea. The capacity of the box can be increased by elongating all its diameters, and this results in air under atmospheric pressure entering the box through the tube. 66
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Now, Consider the 3 diameters of the thoracic cavity and how they may be increased. 1. Vertical Diameter Theoretically, the roof could be raised and the floor lowered. The roof is formed by suprapleural membrane and is fixed. Conversely, the floor is formed by diaphragm. When diaphragm contracts, the domes become flattened and the level is lowered. 2. Antero-posterior (AP) Diameter If we fix the 1 st rib by contraction of the scaleni muscles & intercostal muscles, meaning all the ribs are drawn together and raised toward the 1 st rib & the downward-sloping ribs are raised at their sternal ends, and the lower end of the sternum is thrusted forward. This 'pump handle' type of movement increase the AP diameter of the thorax. 68
3. Transverse Diameter The ribs articulate in front with the sternum via their costal cartilages and behind with the vertebral column. Because the ribs curve downward as well as forward around the chest wall, they resemble bucket handles. It therefore follows that if the ribs are raised (like bucket handles), the transverse diameter of the thoracic cavity will be increased. As described previously, this can be accomplished by fixing the 1 st rib and raising the other ribs to it by contracting the intercostal muscles. 69
Gray s Anatomy for Students 70
Moore Clinically Oriented Anatomy 7 th ed. 71
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VERTICAL DIAMETER The Roof The Floor 73
AP DIAMETER Fixing First Rib Intercostal Muscles 74
TRANSVERSE DIAMETER Fixing First Rib Intercostal Muscles 75
The abdominal muscles play an important role in inspiration. Descent of the diaphragm is accompanied by abdominal Muscle relaxation. Abdominal muscle relaxation reaches its maximum, then the diaphragm is supported from below assisting the intercostal muscles in raising the ribs. 76
This results in maximum increase in the capacity of thoracic cavity. Accessory muscles (scalenus, sternomastoid) helps in more fixing of the first rib. Any muscle which can raise ribs is brought to action. Fixation of the scapulae also occurs. 77
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1. The root descends as much as 2 vertebrae. 2. Bronchi elongate and dilate. 3. Alveolar capillaries dilate. 4. The air is drawn from the positive pressure to the negative one inside. 5. Expansion of the lungs opens the costodiaphragmatic recess. 79
Quiet Expiration (Passive Process) Lung Recoil Relaxation of Muscles Tone of Abd. Muscles 80
Forced Expiration (Active Process) Abd. Muscle Contraction Quadratus Lumborum Pull Of Ribs Downward 81
1. The lung root ascends. 2. Lung tissue recoil and thus decrease in size. 3. The costo-diaphragmatic recess close. 82
In babies & young children, ribs are nearly horizontal. Thus, babies have to rely mainly on the descent of the diaphragm to increase their thoracic capacity on inspiration. They are characterized by marked inward and outward excursion of the anterior abdominal wall, respiration at this age is referred to as the abdominal type of respiration. After the 2nd year of life, the ribs become more oblique, and the adult form of respiration is established. 83
In adults, a sexual difference exists in the type of respiratory movements. The female tends to rely mainly on the movements of the ribs rather than on the descent of the diaphragm on inspiration. This is referred to as the thoracic type of respiration. The male uses both the thoracic and abdominal forms of respiration, but mainly the abdominal form of respiration. 84
The upper zones are best examined from front. The lower lobes are best examined from back. The axilla enables the examination of both upper and lower lobes. 85
The apex of lung is liable for injury in the area above the clavicle. Rib fracture may injure the lung causing leak of air (pneumothorax) and lung collapse. Air may also reach the subcutaneous tissue (subcut. Emphysema) Depending on the phase of respiration abdominal muscles may or may not be injured in penetrating wounds of the lower chest. 86
Pain becomes a prominent feature if the disease involves the parietal pleura which has the characters of pleurisy pain. Pleurisy of the lower parts of the pleura may cause referred pain to the ant. abd. wall. Referred pain over the shoulder region results from irritation of the central part of diaphragmatic pleura. 87
Thoracotomy followed by rib retraction Bilateral anterolateral thoracotomy + transverse sternotomy = "clamshell" incision 88
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Indicated for a localized chronic lesion such as that of tuberculosis or a benign neoplasm. Segmental resection requires that the radiologist and thoracic surgeon have a sound knowledge of the bronchopulmonary segments. 90
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Accounts for about one third of all cancer deaths in men and is becoming increasingly common in women. It mostly commences in the mucous membrane lining the larger bronchi and is therefore situated close to the hilum. The neoplasm rapidly spreads to the tracheobronchial and bronchomediastinal nodes. It may involve the recurrent laryngeal nerves, leading to hoarseness of the voice. Lymphatic spread via the bronchomediastinal trunks may result in early involvement in the lower deep cervical nodes just above the clavicle (supraclavicular L.N). Hematogenous spread to bones and the brain commonly occurs. 92
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It is a chronic inflammatory disease of the lung causing reduction in the diameter of bronchioles by: mucus and constriction. One of the problems associated with bronchial asthma is the spasm of the smooth muscle in the wall of the bronchioles. This particularly reduces the diameter of the bronchioles during expiration, causing the asthmatic patient to experience great difficulty during expiration only. The lungs consequently become greatly distended and the thoracic cage becomes permanently enlarged ( hyper-inflated), forming the so-called barrel chest. 95
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Many Lung diseases (Emphysema and pulmonary fibrosis) destroy the elasticity of the lungs, and makes the lungs unable to recoil causing incomplete expiration. In these patients the expiration is active process. Emphysema: Is characterized by loss of elasticity of the lung tissue, destruction of structures supporting the alveoli, and destruction of capillaries feeding the alveoli. The result is that the small airways collapse during expiration, leading to an obstructive form of lung disease (airflow is impeded and air is generally "trapped" in the lungs in obstructive lung disease. 97
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Diseases such as silicosis, asbestosis, cancer, and pneumonia decrease the compliance of the lungs and the chest wall. Then a greater effort has to be undertaken by the inspiratory muscles to inflate the lungs during inspiration. 99
Excessive accumulation of bronchial secretions in a lobe or segment of a lung can seriously interfere with the normal flow of air into the alveoli. Furthermore, the stagnation of such secretions is often quickly followed by infection. To aid in the normal drainage of a bronchial segment, a physiotherapist often alters the position of the patient so that gravity assists in the process of drainage. Sound knowledge of the bronchial tree is necessary to determine the optimum position of the patient for good postural drainage. 100
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