Anatomy of Thorax & Chest PDF

Anatomy of thorax & chest Dr.Maha Samir Younis Lecturer of pt for cardiopulmonary disorders and its surgery Department of internal pt – May UNIVERSITY  Thorax Area between head and abdomen contains heart, lung and blood vessels Surrounded by thoracic cage formed of:...

Anatomy of thorax & chest Dr.Maha Samir Younis Lecturer of pt for cardiopulmonary disorders and its surgery Department of internal pt – May UNIVERSITY  Thorax Area between head and abdomen contains heart, lung and blood vessels Surrounded by thoracic cage formed of: 12 ribs Sternum Thoracic vertebrae Clavicle Intercostal muscles Set of 12 ribs Articulates posteriorly with vertebral column from Ribs T1-T12 Terminate anterior with cartilage called costal cartilage Types of ribs: 1. True ribs (vertebrosternal) attached to sternum from 1- 7 2. False ribs: doesn’t connect to sternum Last 5 ribs (8 to 12) 1st 3 pairs called vertebrochondlar as they connect to sternum through costal cartilage of rib above Last 2 pairs are floating ribs as they connect to vertebrae alone Space between ribs called intercostal space and contains intercostal muscles, neuromuscular bundles and intercostal nerves, veins, arteries. Superficial surface of rib cage is covered with thoracolumbar facia which gives attachment to neck, pectorals, back and abdominal muscles.  Each rib consists of: 1. Head: articulate with thoracic vertebrae through (superior costal facet of same vertebra, inferior costal facet of upper vertebra, transverse costal facet of same vertebra) 2. Neck: extends 3 cm laterally from the head and has 2 surfaces (anterior soft surface and posterior rough surface for the attachment of costotransverse ligament. 3. Shaft contains angle of the rib and extends downward and laterally Sternum  Flat vertical bone at center of chest  To protect heart and muscles  Connect the ribs through costal cartilage to form anterior rib cage  Divided to: 1. Manubrium: superior segment 2. Body: a middle portion 3. Xiphoid process: narrow distal segment  STERNUM COMMON DEFORMITIES 1. Pectus excavatum (funnel chest)  More common  Sternum depressed posteriorly leading to depression of adjacent costal cartilage inward and depression of anterior chest wall 2. Pectus carinatum:  Outward displacement of sternum and costal cartilage leading to abnormal Pectus excavatum Pectus carinatum protrusion of anterior chest wall  Diaphragm This muscle separating thoracic cavity from abdominal cavity When it’s relaxed its dome shape (during expiration) When it contracts it’s flattened to increase the volume in the thoracic cavity (during inspiration) Structure: Upward curved, c shape structure of muscle and fibrous tissue Separate thoracic cavity from abdominal cavity Formed of: Central tendon forms the crest of the dome Peripheral fibers  Contains several openings mainly: 1. Caval opening in central tendon contain inferior vena cava 2. Esophageal hiatus contains esophagus in posterior part of diaphragm 3. Aortic hiatus: contains aorta and thoracic duct in posterior part of diaphragm  Nerve supply: Central part phrenic nerve (c3-c5) Peripheral part by intercostal nerves (T5-T11), subcostal nerve T12  Function: Main muscle of respiration  During inhalation: Diaphragm contracts and moves inferior direction led to increase volume of thoracic cavity, decreasing intrathoracic pressure so air moves in (with help of external intercostal muscles)  During exhalation: Diaphragm relaxed so air moves move out by the elastic recoil of diaphragm with assist of internal intercostal muscles and abdominal muscles in forced expiration. Diaphragm movement during respiration  Diaphragmatic dysfunction can be categorized into Functional disorders that lead to decreased muscle function, ranging from muscle fatigue or weakness, to complete paralysis. As in COPD , mechanical ventilation patient or myopathies.  Anatomical disorder that are characterized by normal function of the diaphragm but limited movement due to structural and anatomical derangement. These disorders include herniation of the diaphragm and diseases of the other related organs obstructing its movement  INTERCOSTAL MUSCLES Function: 1. Helps to move chest wall 2. Involved in mechanical aspect of breathing 3. Helps to expand and shrink the size of chest cavity Nerve supply is intercostal nerves mainly ventral rami of thoracic spinal nerve Supplied by intercostal arteries and drained by intercostal veins.  Intercostal muscles layering 1. External intercostal muscles: Function: quiet and forced inhalation Origin: ribs 1-11 Insertion: ribs 2-12 Direction downward, forward, medially 1. Internal intercostal muscles: Function: forced expiration Origin from rib 2-12 Insertion on ribs 1-11 Direction upward Forword laterally 1. Innermost intercostal muscles: Deep layer of int intercostal muscles Fibers direction: downward, forward, laterally Separated from int intercostal muscles with neurovascular bundle Function: Depress ribs during forced expiration; Support intercostal spaces and thoracic cage Accessory muscles of respiration  1-Scalene muscles:  Group of muscles on each side of neck  Divided to (anterior, middle, posterior)  Innervated by spinal nerves C3-C8  Moves chest wall and assist inhalation  2-Sternocleidomastoid muscle: Runs from head and neck to sternum and first 2 ribs This muscle elevates the sternum thus increasing anterior posterior diameter of chest  3-Upper trapezius  Assists in ventilation by helping elevation thoracic cage  4-Pectoralis muscles  Pectoralis major increase anteroposterior diameter of chest  Pectoralis minor assist in raising the ribs and increasing intrathoracic volume Cont. accessory muscles of respiration  5-Abdominal muscles Including rectus abdominis, transverse abdominis, internal and external obliques. *Theses muscles work to increase intraabdominal pressure when sudden expulsion of air is required as in huffing or coughing.  HEART Size: Approximately the size of man fist (250-350) Is a muscular organ acts like a pump to gm continuously send blood through the body. Heart shape: Location of heart: 1.Apex: Directed downward and forward to left Formed by left ventricle Underneath the sternum in a thoracic At level of 5th intercostal space, 3.5 inch compartment called mediastinum which from midline directly under the nibbes occupies space between the lung 2.Sternocostal surface (anterior surface) Formed of right atrium, right ventricle 2/3, left ventricle 1/3 3.Diaphragmatic surface: (inferior surface) Directed inferior and backward Formed by two ventricles mainly 2/3 of left ventricle Slightly concave as it rests on diaphragm 4.Base of heart (posterior surface): Formed by two atria mainly left atrium Opposite to thoracic vertebrae (T5,6,7)  Pericardium: Is a fibrous sac surround the heart Function: 1. Fluid within the sac lubricate the outer wall of the heart to decrease friction 2. Hold heart in place 3. Prevent heart over expanding 4. Form a barrier against infections  PERICARDIUM LAYERS Formed of: Fibrous pericardium (PARIETAL) outer thick wall formed of dense irregular connective tissue Serous pericardium (VISCERAL) inner wall formed of parietal and visceral pericardium Pericardial cavity: space between 2 walls filled with (10-15) pericardial fluid  LAYERS OF HEART WALL 1. Epicardium: covering the outer layer of heart 2. Myocardium: thick middle layer, during contraction it pumps blood out through aorta and pulmonary trunk 3. Endocardium: covering the inner surface of heart, valves, and tendons  Champers &Valves of heart 1- Right atrium: Formed of main cavity and upward protrusion called auricle Openings in right atrium: superior vena cava and inferior vena cava (which deliver poor oxygenated blood from upper and lower body) coronary sinus blood leaves right atrium to right ventricle through tricuspid valve 2- Right ventricle: Pumps poor oxygenated blood to lung Has thinner wall than left ventricle Blood leaves right ventricle to pulmonary trunk through pulmonary orifice 3- Left atrium: Receives oxygenated blood from lung through pulmonary veins Forms the greater part of heart base Receives 4 pulmonary veins 4- Left ventricle: Has thicker wall than right ventricle Receive blood from left atrium through mitral valve (bicuspid valve) Blood leaves left ventricle through ascending aorta to deliver oxygenated blood to the body  Heart valves: 1. Atrioventricular valves: *Tricuspid valve between right atrium and right ventricle *Mitral valve between left atrium and left ventricle 1. Semilunar valves: Open when blood flow out of ventricles *Pulmonary valve: open when blood flow from right ventricle blood to pulmonary artery (the only artery carries deoxygenated blood to lung) *Aortic valve: opens when blood flow from left ventricle to aorta  HEART VALVE DISEASES 1.regurgitation (or leakage of the valve): The valve(s) does not close completely, causing the blood to flow backward through the valve. This results in leakage of blood back into the atria from the ventricles (in the case of the mitral and tricuspid valves) or leakage of blood back into the ventricles (in the case of the aortic and pulmonary valves). 2.stenosis (or narrowing of the valve): The valve(s) opening becomes narrowed or valves become damaged or scarred (stiff), inhibiting the flow of blood out of the ventricles or atria. The heart is forced to pump blood with increased force in order to move blood through the narrowed or stiff (stenotic) valve(s) How much blood does your heart pump? Your heart pumps about 2,000 gallons of blood each day. That’s enough to fill an 8-by-10-foot swimming pool. It beats around 100,000 times daily. In an average life span of almost 79 years, your heart beats nearly 2.9 billion times Normal heart beat: Children 5-6 years → 75-115 BPM Children 7-9 years → 70-110 PBM Children > 10 years, adults and seniors → 60-100 PBM Athletes in top condition → 40-60 PBM  CIRCULATION OF THE HEART On the right side 1.Oxygen-poor blood from all over your body enters your right atrium through two large veins, your superior vena cava and inferior vena cava. These veins drain blood from your upper body and lower body, respectively, and directly empty it into your right atrium. 2.Your tricuspid valve opens to let blood travel from your right atrium to your right ventricle. 3.When your right ventricle is full it squeezes, which closes your tricuspid valve and opens your pulmonary valve. 4.Blood flows through your main pulmonary artery and its branches to your lungs, where it gets oxygen and releases carbon dioxide. On the left side 1.Oxygen-rich blood travels from your lungs to your left atrium through large veins called pulmonary veins. These veins directly empty the blood into your left atrium. 2.Your mitral valve opens to send blood from your left atrium to your left ventricle. 3.When your left ventricle is full it squeezes, which closes your mitral valve and opens your aortic valve. 4.Your heart sends blood through your aortic valve to your aorta, where it flows to the rest of your body  Coronary arteries Supply nutrients to the heart & runs along its surface 1. Left coronary artery divided to: Circumflex artery supply blood to left atrium and side and back of left ventricle Left anterior descending artery supply blood to front and bottom of left ventricle and front of septum 2. Right coronary artery: Supply blood to right atrium and right ventricle, back of septum  Medical Conditions affecting the heart: Arrhythmia: An irregular heartbeat like atrial fibrillation or ventricular fibrillation. Congestive heart failure: Damage or weakness in your heart muscle, making it harder for your heart to pump blood to the rest of your body. Coronary artery disease (CAD): Hardening and narrowing of the arteries that carry blood to your heart muscle due to plaque buildup. Peripheral artery disease (PAD): Hardening and narrowing of the arteries that carry blood to the rest of your body due to plaque buildup. Heart attack: A sudden blockage in your coronary artery that cuts off oxygen to part of your heart muscle. Heart valve disease: A heart valve that doesn’t work properly. For example, it may be narrowed or leaky. Structural congenital heart defects: Problems with your heart structure that are present at birth, including bicuspid aortic valve disease.( Fallot disease) Sudden cardiac arrest: Sudden loss of heart function because of a malfunction in your heart’s electrical system  Electrical conduction system of the heart 1- Sinoatrial node (SA) Send signals to make heart beat 2- Atrioventricular node (AV) Carry signals from heart upper champers to lower champers 3- Left bundle branch: Send impulses to left ventricle 4- Right bundle branch: Send impulses to right ventricle 5- Bundel of Hiss: Send impulses from AV node to Purkinje fibers 6- Purkinje fibers: Make heart contract to pump blood  RESPIRATORY SYSTEM PRIMARY FUNCTION OF RESPIRATORY SYSTEM: 1. exchange gases between atmosphere and blood 2. homeostatic regulation of body PH 3. Protect against inhaled pathogens and irritating substances 4. Vocalization Process of external respiration 1.Exchange 1 (ventilation) Exchange of gases between atmosphere and lung through inhalation and exhalation 2.Exchange 2 Exchange of O2 and CO2 between lung and blood 3.Transport of O2 and CO2 BY BLOOD 4.Exchange 3: Gas exchange between blood and body cells Respiratory airway Leads from external environment to exchange surface of lung 1- upper respiratory tract (mouth, nasal cavity, larynx, pharynx) 2- lower respiratory tract (trachea, 2 primary bronchi, bronchioles, 2 lungs) Role of airway: 1. Warming air 2. Adding water vapor 3. Filtering out foreign materials Nose or mouth→ pharynx→ larynx→ trachea→ primary bronchi→ secondary bronchi→ bronchioles→ alveoli (exchange surface of O2 &CO2 with blood)  Alveoli It is the exchange surface of O2 & CO2 between blood and lungs Formed of single layer of epithelium Types: 1. Type 1 alveolar cells (95%) Large, thin, allows rapid gas exchange 1. Type 2 alveolar cells (5%) Small, thick, responsible for synthesis and storage of pulmonary surfactant (↓ surface tension and allows expansion of alveoli) No. of alveoli >400,000,000  Bronchial Tree Trachea divides in to 2 main bronchi (primary bronchi) at level of sternal angle at T4 vertebra Each main bronchi enters the lung inferior and lateral through the hila Right main bronchus is wider than left main bronchi The main (primary) bronchi subdivided to secondary lobber bronchi Right lung has 3 lobber bronchi Left lung has 2 lobber bronchi Each lobber bronchi subdivided to segmental bronchi There are ten bronchopulmonary segments in right lung and eight at left lung Segmental bronchi subdivide to bronchioles Type of bronchioles: 1- Conductive (20-25) branch 2- Terminal 3- Respiratory which gives rise to alveolar duct and alveolar sac  LUNGS Light spongy organs with volume filled with air filled spaces Formed of: 1. Apex: lies above first rib and covered with cervical pleura 2. Base: concave inferior surface resting on diaphragm 3. Surfaces: Costal surface related to (sternum, ribs, costal pleura) Mediastinal surface related to middle mediastinum which means between 2 lungs contain heart & pericardium Diaphragmatic surface: concave resting on diaphragm dome (right dome is higher than left dome due to liver) 1. Borders of lung: Anterior border (having cardiac notch at left lung) Inferior border (separate lung base from costal surface) Posterior border (extends from lung apex to inferior border) 1. Lobes of lung: Right lung: upper, middle, lower Left lung: upper, lower 1. Fissures of lung: Right lung: Transverse fissure at level of 4th rib Oblique fissure extends from T2 to 6 costal spaces Left lung: Oblique fissure extends from T2 to 5 costal spaces 1. Segments of lung: Right lung: Upper lobe (apical, anterior, posterior) Middle lobe (medial, lateral) Lower lobe (superior, anterior, posterior, medial, lateral) Left lung: Upper lobe (anterior, inferior, apical posterior, superior lingula) Lower lobe (lateral, posterior, superior, anteromedial) LUNGS LOBES & SEGMENTS  PLEURAL SPACE Pleural space: Thin fluid filled cavity located between the lung and chest wall inner surface Formed of: Visceral pleura covers the lung Parietal pleura lines the inner surface of chest wall Secrets pleural fluid that lubricates and ↓friction during breathing Blood supply to lungs through brachial arteries  Nerve supply to lungs: Pulmonary plexus: -Parasympathetic stimulation (vagal nerve) - Sympathetic stimulation Phrenic nerve  Lung defenses  Nasal mucosa and hairs warm and humidify inhaled air and filter out particles  Goblet cells and bronchial seromucous glands produce mucus which contains immunoglobulin A to protect underlying tissues and trap organisms and particles Mucus production may be increased by inflammation ( asthma, bronchitis)  Alveolar macrophages roam the surface of the terminal airways and engulf foreign matters and bacteria, their activity may be impeded by cigarette smoke, air pollution, corticosteroid therapy and alcohol  Type II pneumocytes produce surfactant which protect underlying tissues and repairs damaged alveolar epithelium  Respiratory tract is protected by different mechanisms in different levels: 1.Upper airways (physical mechanisms like coughing and sneezing) 2.Lower airways (mucociliary clearance mechanisms) 3.Terminal bronchioles and alveoli (surfactant and cellular defenders and alveolar macrophages)  Nasal irritation  Afferent impulse through Sneeze reflex trigeminal and olfactory nerves  Medulla triggering reflex  Efferent impulses  eye closing  deep inspiration  a forced expiration with initial closing of the glottis, and increasing intrapulmonary pressure  The sudden dilatation of the glottis and uvula depression  an explosive exit of air through the mouth and nose, washing out mucosal debris and irritants  Ventilation: Air flows in and out due to pressure gradient, from area of high pressure to low pressure Flows in when pressure in < pressure out Flows out when pressure in > pressure out  Boyle’s law Pressure inversely proportional to volume Ex. To allow inhalation (flow in air) pressure must ↓so volume must ↑ Muscles of ventilation:  During inspiration: Diaphragm External intercostal muscles, sternocleidomastoid, scaleni  During expiration: Rest: passive recoil of diaphragm Forced expiration: abdominal muscles push diaphragm up Internal intercostal muscles pull ribs down MECHANISM OF RESPIRATION highest ventilation in the lower lung  Respiratory Features Ventilation refers to the flow of air into and out of the alveoli affected by gravity and difference in intra pleural pressure. Ventilation is greatest in lower lung than upper lung region Airway resistance: upper airways provide 45% of total airway resistance Lower airway may be narrowed due to: normal expiration, external pressure due to tumor or pleural effusion, bronchoconstriction, mucosal congestion Compliance: how easily the lung inflates during inspiration Decreased by fibrosis, edema, pleural effusion Increased by age, emphysema Diffusion: the spontaneous movement of gases, without the use of any energy or effort by the body, between the alveoli and the capillaries in the lungs alveolar capillary interface Decreased by thickening, fibroids, edema Perfusion: refers to the flow of blood to alveolar capillaries Affected by body position & hydrostatic pressure Lower lung has greater perfusion than upper lung Ventilation- perfusion matching (V/Q) perfusion increases more than ventilation at the base of the lung, resulting in lower V/Q ratios in the base of the lung compared to the apex. In a healthy individual, the V/Q ratio is 1 at the middle of the lung, with a minimal spread of V/Q ratios from 0.3 to 2.1 from base to apex abnormal ratio results from: Uneven compliance due to fibrosis or emphysema Uneven airway resistance due to bronchoconstriction or tumors Obstruction of pulmonary circulation due to thrombosis, fat embolus Compression of blood vessels due to over expanded alveoli  Exercise physiology & ventilation: During exercise the respiratory system must increase the volume of air (Oxygen) that is ventilated by the lungs (i.e., minute ventilation, which is usually measured during expiration and thus referred to as VE) and diffused into the blood for delivery to the exercising muscles. At rest, VE is usually 5 to 10 L/min and it often increases 15- to 20- fold during maximal exercise. At the onset of mild to moderate exercise, VE typically increases via increasing tidal volume. During more strenuous exercise, rising respiratory rates further augment VE. VE Increases in direct proportion to oxygen consumption (VO2) and carbon dioxide production (VCO2) until exercise intensity exceeds the ventilatory threshold (generally about 50% to 70% of V O2max, when there are abrupt nonlinear increases in lactate and VCO2). At this point VE also increases disproportionately with VO2.  Respiratory rate & depth control: Brainstem control Medulla respiratory center: 1.Medullary rhythmicity area: Maintains basic rhythm between inspiration and expiration Pons respiratory control: 1. Pneumotaxic area: stimulate expiration 2.Apneustic area: Activate and prolong inspiration  Other controls of respiration rate & depth 1. higher brain centers (cerebral cortex) have voluntary control over breathing 2. receptors in muscles and joints (proprioceptors) when stimulated, it increases breathing 3. pain: sudden pain can cause apnea (cessation of breathing while prolonged pain increase breathing 4. temperature: increase temperature leads to increase respiratory rate and vice versa 5. blood pressure: ↓BP → Increase respiratory rate ↑BP→ Decrease respiratory rate 6-Hering Breur reflex: Prevents over stretching of lung due to stretching receptors throughout the lung With stretching, vagus nerve stimulates to inhibit apneustic area, and allow pneumotaxic area to dominate allowing expiration 7-CO2 level: Hypercapnia: Increase in PCO2 stimulate apneustic area Ex. Holding breath →build up CO2→↑Breathing to equalize PCO2 in vessels Increase CO2 = Increase breathing = Increase hyperventilation to decrease the CO2 level Hypocapnia: Blown off CO2 leads to decrease PCO2 leads to decrease respiration to stabilize CO2 level Decrease Breathing = Decrease Respiration to stabilize CO2 levels  Lung volumes and capacities Tidal Volume (TV) It is the amount of air that can be inhaled or exhaled during one respiratory cycle Inspiratory Reserve Volume (IRV) It is the amount of air that can be forcibly inhaled after a normal tidal volume Expiratory Reserve Volume (ERV) It is the volume of air that can be exhaled forcibly after exhalation of normal tidal volume. Residual Volume (RV) It is the volume of air remaining in the lungs after maximal exhalation  Inspiratory capacity (IC) It is the maximum volume of air that can be inhaled following a resting state Total Lung Capacity (TLC) It is the maximum volume of air the lungs can accommodate or sum of all volume compartments or volume of air in lungs after maximum inspiration. Vital Capacity (VC) It is the total amount of air exhaled after maximal inhalation Function Residual Capacity (FRC) It is the amount of air remaining in the lungs at the end of a normal exhalation