Unit 3 - Thorax PDF

Diploma in Physiotherapy Please do not reproduce, redistribute or share without the prior express permission of the author. Lecture notes ANATOMY II THORAX Please do not reproduce, redistribute or share without the prior express permission of the author. Please do not re...

Diploma in Physiotherapy Please do not reproduce, redistribute or share without the prior express permission of the author. Lecture notes ANATOMY II THORAX Please do not reproduce, redistribute or share without the prior express permission of the author. Please do not reproduce, redistribute or share without the prior express permission of the author.  Learning Outcome At the end of the lesson, students will be able to: Describe the structure of the thoracic cavity and their boundaries. Understand the features of the bone and joints of thoracic cage and their movements Explain the gross anatomy of right and left lung. Explain the structure and functions of the heart. Describe the factors affecting the lungs and heart. Please do not reproduce, redistribute or share without the prior express permission of the author.  Thoracic Cavity & Pleurae The thoracic cavity (or chest cavity) is the chamber of the human body that is protected by the thoracic wall (thoracic cage and associated skin, muscle, and fascia). It contains three potential spaces lined with mesothelium: the paired pleural cavities and the pericardial cavity. The mediastinum comprises those organs which lie in the centre of the chest between the lungs. Please do not reproduce, redistribute or share without the prior express permission of the author. Please do not reproduce, redistribute or share without the prior express permission of the author.  Thoracic cavity contains right and left pleural cavities, which are occupied by lungs The right and left pleural cavities are separated by a thick median partition called the mediastinum, where the heart is located. Please do not reproduce, redistribute or share without the prior express permission of the author.  Components Structures within the thoracic cavity include: The cardiovascular system, including the heart and great vessels, which include the thoracic aorta, the pulmonary artery and all its branches, the superior and inferior vena cava, the pulmonary veins, and the azygos vein The respiratory system, including the trachea, bronchi and lungs The digestive system, including the esophagus The Endocrine glands, including the thymus gland The nervous system including the paired of vagus nerves, and the paired sympathetic chains, lymphatics including the thoracic duct. Please do not reproduce, redistribute or share without the prior express permission of the author. Please do not reproduce, redistribute or share without the prior express permission of the author.  Boundaries The thoracic cavity is separated from the abdominal cavity by the diaphragm. An Osseo cartilaginous, elastic cage designed for increasing and decreasing the intra-thoracic pressure, to allow air to be sucked in during inspiration and expelled during expiration. Formed by – anteriorly by sternum, posteriorly by 12 thoracic vertebrae & intervening intervertebral discs and on each side by the 12 ribs with their cartilages. Please do not reproduce, redistribute or share without the prior express permission of the author. Please do not reproduce, redistribute or share without the prior express permission of the author.  Bones and joints of the thorax Bones are: Ribs (12 ribs on each side) Sternum Vertebral column or spine Please do not reproduce, redistribute or share without the prior express permission of the author.  Bony Thorax (Thoracic Cage) (8 – 10) Please do not reproduce, redistribute or share without the prior express permission of the author.  Sternum (Breastbone) A dagger-shaped, flat bone that lies in the anterior midline of the thorax. Results from the fusion of three bones – the superior manubrium, the body, and the inferior xiphoid process. Anatomical landmarks include the jugular (suprasternal) notch, the sternal angle, and the xiphisternal joint Please do not reproduce, redistribute or share without the prior express permission of the author. Please do not reproduce, redistribute or share without the prior express permission of the author. Please do not reproduce, redistribute or share without the prior express permission of the author. Please do not reproduce, redistribute or share without the prior express permission of the author.  Ribs There are twelve pair of ribs forming the flaring sides of the thoracic cage. All ribs attach posteriorly to the thoracic vertebrae. The superior 7 pair (true ribs, or vertebrosternal ribs) attach directly to the sternum via costal cartilages. Ribs 8-10 (false, or vertebrocondral ribs) attach indirectly to the sternum via costal cartilage. Ribs 11-12 (floating, or vertebral ribs) have no anterior attachment. Please do not reproduce, redistribute or share without the prior express permission of the author.  Rib costal groove Shaft Tubercle Neck Head Please do not reproduce, redistribute or share without the prior express permission of the author. Please do not reproduce, redistribute or share without the prior express permission of the author.  Structure of a typical true rib Bowed, flat bone. A typical rib has the following characteristics: Head -- articulates with bodies of vertebrae. Neck. Tubercle -- articulates with transverse processes. Angle -- a point just lateral to the tubercle where the shaft bends forward; costal groove -- lodges intercostal vessels and nerves. Please do not reproduce, redistribute or share without the prior express permission of the author. Typical rib Please do not reproduce, redistribute or share without the prior express permission of the author.  Thoracic vertebrae (T1 – T12) The thoracic vertebrae increase in size from T1 through T12. They are characterized by small pedicles, long spinous processes, and relatively large intervertebral foramen (neural passageways), which result in less incidence of nerve compression. The special characteristics of the thoracic vertebrae is that the bodies and transverse process have facets for articulation with the ribs. The location of the articulate facets prevents flexion and extension, but allows rotation of this area of the spine Please do not reproduce, redistribute or share without the prior express permission of the author. Please do not reproduce, redistribute or share without the prior express permission of the author. Please do not reproduce, redistribute or share without the prior express permission of the author. Joints are: Manubriosternal joints Costovertebral joints Costotransverse joints Costochondral joints Chondrosternal joints Interchondral joints Please do not reproduce, redistribute or share without the prior express permission of the author.  Costovertebral joints: Synovial joint formed by the head of the rib, 2 adjacent vertebral bodies and the interposed intervertebral disk. Ribs 2 – 9 have typical costovertebral joint. 1st, 10th, 11th and 12th ribs are atypical ribs as they articulate with only one vertebra. The typical CV joint is divided into 2 cavities by the interosseous or intra- articular ligament. The radiant ligament is located within the capsule, with firm attachments to the anterolateral portion of the capsule. Please do not reproduce, redistribute or share without the prior express permission of the author.  A fibrous capsule surrounds the entire articulation of each CV joint. The atypical CV joints of ribs 1 to 10 through 12 are more mobile than the typical CV joints. The interosseous ligament is absent in these joints. The radiate ligament is present in these joints. Both rotation and gliding motions occur at all of the CV joints. Please do not reproduce, redistribute or share without the prior express permission of the author. Please do not reproduce, redistribute or share without the prior express permission of the author.  Costotransverse joints: The CT joint is a synovial joint formed by the articulation of the costal tubercle of the rib with a costal facet on the transverse process of the corresponding vertebra. There are 10 pairs of CT joints articulating 1 to 10 thoracic vertebra with 1 – 10 ribs. T1 – T6 Ct joints have concave costal facets on the transverse process of the vertebrae and convex costal tubercles on the corresponding ribs, thus allowing slight rotation movement between the segments. Please do not reproduce, redistribute or share without the prior express permission of the author.  From T7 through T10, both articulating surfaces are flat and gliding motion is predominant. Ribs 11 and 12 do not articulate with the respective transverse process of T11 and T12 vertebrae. The CT joint is surrounded by a thin capsule. There are 3 major ligaments: lateral costotransverse ligament, the costotransverse ligament, and the superior costotransveerse ligament. Please do not reproduce, redistribute or share without the prior express permission of the author. Please do not reproduce, redistribute or share without the prior express permission of the author.  Costochondral and condrosternal joints: The costochondral joints are formed by the articulation of 1st through 10th ribs with the costal cartilages. The CC joints are synchondroses with no ligament support. The costo sternal joints are formed by the articulation of ribs 1 to 7 with the stermum. Rib 1 attaches to the lateral facet of the manubrium, rib 2 is attached via 2 demifacets at the manubriosternal junction & rib 3 through 7 articulate with the lateral facets of sternal body. Please do not reproduce, redistribute or share without the prior express permission of the author.  The CS joints of the 1st, 6th and 7th ribs are synchonroses and joints of 2nd to 5th ribs are synovial joints The CS joints of 1st to 7th ribs have capsule and ligamentous support. The ligaments include anterior and posterior radiate costosternal ligament, sternocostal ligament and costoxiphoid ligament. Please do not reproduce, redistribute or share without the prior express permission of the author.  Interchondral joints: The 7th through 10th costal cartilages each articulate with the cartilage immediately above them. For the 8th through 10th ribs, this artriculation forms only connection to the sternum. The interchondral joints are synovial joints and are supported by a capsule and interchondral ligaments. The interchondral articulations tend to become fibrous and fuse with age. Please do not reproduce, redistribute or share without the prior express permission of the author.  Movements of the Thorax BUCKET-HANDLE MOVEMENT PUMP-HANDLE MOVEMENT Please do not reproduce, redistribute or share without the prior express permission of the author. Muscles associated with rib cage: These muscles are generally termed as ventilatory muscles. The ventilatory muscles are classified into: Primary muscles of ventilation Accessory muscles of ventilation Please do not reproduce, redistribute or share without the prior express permission of the author.  Primary muscles of ventilation: Diaphragm Intercostal muscles Scalene muscle Please do not reproduce, redistribute or share without the prior express permission of the author. Please do not reproduce, redistribute or share without the prior express permission of the author.  Diaphragm: The diaphragm is accounting for 70% to 80% of inspiration force during quite breathing. It arises from sternum, costocartilages, ribs and vertebral bodies. It is inserted into central tendon. Functionally divided into costal portion and crural portion. Please do not reproduce, redistribute or share without the prior express permission of the author.  The costal portion is attached to the posterior aspect of the xiphoid process and inner surfaces of the lower 6th ribs and costal cartilages. The vertical fibers which lie close to the inner wall of the lower rib cage are termed as zone of apposition. The crural portion arises from anterolateral surfaces of the bodies and discs of L1 to L3 vertebra. Please do not reproduce, redistribute or share without the prior express permission of the author. Please do not reproduce, redistribute or share without the prior express permission of the author.  Intercostal muscles: The external and internal intercostal muscles are categorized as ventilatory muscles. The internal and external intercostal and the subcostals muscles connect adjacent ribs to one another. The subcostal muscles are generally found in the lower rib cage. The external intercostal muscles tend to raise the lower rib up to the higher rib, which is an inspiratory motion. Please do not reproduce, redistribute or share without the prior express permission of the author. Please do not reproduce, redistribute or share without the prior express permission of the author. Scalene muscles: They lift the sternum and the first 2 ribs in the pump handle movement of the upper rib cage. The scalene muscles also function as stabilizers of the rib cage. Please do not reproduce, redistribute or share without the prior express permission of the author. Accessory muscles of ventilation: The muscles that attach the rib cage to the shoulder girdle, head, vertebral column, or pelvis may be classified as accessory muscles of ventilation. These muscles assist with inspiration or expiration in situations of stress, such as increased activity or disease. With the help of the trapezius muscle stabilizing the head, the bilateral action of the sternocleidomastoid muscles moves the rib cage superiorly, which expands the upper rib cage in the pump-handle motion. Please do not reproduce, redistribute or share without the prior express permission of the author.  The sternocostal portion of the pectoralis major muscle can elevate the upper rib cage when the shoulders and the humerus are stabilized. The clavicular head of the pectoralis major can be either inspiratory or expiratory in action, depending on the position of the upper extremity. Please do not reproduce, redistribute or share without the prior express permission of the author.  The pectoralis minor can help elevate the third, fourth, and fifth ribs during a forced inspiration. The subclavius, a muscle between the clavicle and the first rib, can also assist in raising the upper chest for inspiration. Posteriorly, the fibers of the levatores costarum can assist with elevation of the upper ribs. The serratus posterior superior (SPS) elevates the ribs and the serratus posterior inferior (SPI) lowers the ribs and stabilize the diaphragm Please do not reproduce, redistribute or share without the prior express permission of the author. Please do not reproduce, redistribute or share without the prior express permission of the author. Please do not reproduce, redistribute or share without the prior express permission of the author. Please do not reproduce, redistribute or share without the prior express permission of the author. Please do not reproduce, redistribute or share without the prior express permission of the author.  Muscles of Expiration The abdominal muscles (transversus abdominis, internal oblique abdominis, external oblique abdominis, and rectus abdominis) are expiratory muscles The major function of the abdominal muscles with regard to ventilation is to assist with forced expiration. Please do not reproduce, redistribute or share without the prior express permission of the author.  The transversus thoracis muscles are recruited for ventilation along with the abdominal muscles. These muscles are also primarily expiratory muscles, especially when expiration is active, as in talking, coughing, or laughing, or in exhalation into functional residual capacity. Please do not reproduce, redistribute or share without the prior express permission of the author. Please do not reproduce, redistribute or share without the prior express permission of the author. Please do not reproduce, redistribute or share without the prior express permission of the author.  Lungs A pair of respiratory organs situated in the thoracic cavity within the pleural cavity, separated by the mediastinum Spongy in texture, in the young the lungs are brown or grey, but gradually becomes mottled black because of the deposition of carbon particles. Please do not reproduce, redistribute or share without the prior express permission of the author.  Position of lungs in the thoracic cavity The lungs serve as the gas-exchanging organ for the process of respiration. The lungs are two broad, cone-shaped organs located on either side of the heart in the thoracic cavity. Each lung has: 1. an apex - at the upper end 2. a base resting on the diaphragm 3. three borders - anterior, posterior and inferior 4. two surfaces - costal and medial (vertebral and mediastinal parts) Please do not reproduce, redistribute or share without the prior express permission of the author.  Each lung is divided into lobes separated by deep grooves or fissures. The right lung, which is larger, is divided into three lobes. The left lung is divided into only two lobes. Please do not reproduce, redistribute or share without the prior express permission of the author. Please do not reproduce, redistribute or share without the prior express permission of the author.  Gross anatomy of right and left lung A membrane sac, called the pleura, surrounds and protects each lung. One layer of the pleura attaches to the wall of the thoracic cavity; the other layer encloses the lung. A fluid (pleural fluid) between the two membrane layers reduces friction and allows smooth movement of a lung during breathing. Right and left lungs are separated by the mediastinum. Please do not reproduce, redistribute or share without the prior express permission of the author.  Pleura The outer layer – Parietal pleura, it is subdivided into costal, diaphragmatic, mediastinal and cervical. The inner layer – Visceral or pulmonary layer. Please do not reproduce, redistribute or share without the prior express permission of the author.  Fissures and lobes of lungs Right lung is divided into 3 The left lung is divided into lobes – superior, middle and two lobes by the oblique inferior by two fissures – fissure oblique and horizontal Please do not reproduce, redistribute or share without the prior express permission of the author.  The trachea divides behind the sternum to form a right and left branch called primary bronchi. After the bronchi enter the lungs, they subdivide repeatedly into smaller and smaller bronchi or branches. Eventually they form thousands of tiny branches called bronchioles, which have a diameter of about 0.02 inch (0.5 millimeter). This branching network of bronchial tubes within the lungs is called the bronchial tree Please do not reproduce, redistribute or share without the prior express permission of the author. Please do not reproduce, redistribute or share without the prior express permission of the author.  Bronchopulmonary segments They are well defined sectors of the lung, each one of which is aerated by a tertiary or segmental bronchus,10 segments on the right and 8 on the left. Each segment is pyramidal in shape with its apex directed towards the root of the lung. Significance – postural drainage. Please do not reproduce, redistribute or share without the prior express permission of the author. Please do not reproduce, redistribute or share without the prior express permission of the author. Please do not reproduce, redistribute or share without the prior express permission of the author. Please do not reproduce, redistribute or share without the prior express permission of the author.  It is the space between lungs from inlet to Mediastinum outlet of thorax Anteriorly it is between parasternal lines Posteriorly it is at vertebral line. Superiorly it starts at suprasternal notch. Inferiorly it extends to xiphisternum. The mediastinum is divided into superior and inferior, its is further divided into three compartments—the anterior , middle, and posterior. Please do not reproduce, redistribute or share without the prior express permission of the author.  LOCATION AND POSITION OF THE HEART Heart is a conical, hollow muscular organ situated in the middle mediastinum. It lies in the thoracic cavity in the mediastinum between lungs. Heart is placed obliquely behind the body of sternum and adjoining parts of the costal cartilages. It lies with the base above, and an apex below. 1/3 of it lies to the right and 2/3 to the left of median plane. Apex is about 9cm to the left of the midline at the level of the 5th intercostal space, i.e., a little below the nipple and slightly nearer the midline. The base extends to the level of the 2nd rib. Please do not reproduce, redistribute or share without the prior express permission of the author.  LAYERS OF THE PERICARDIUM Pericardium is a fibroserous sac which encloses the heart. It is situated in the middle mediastinum. It consists of fibrous pericardium and serous pericardium. Serous pericardium has a parietal and a visceral layer. In between the parietal and visceral pericardial layers there is a potential space called the pericardial cavity. It is normally lubricated by a film of pericardial fluid. Please do not reproduce, redistribute or share without the prior express permission of the author.  Structure & Functions Of The Heart Human heart has four chambers – the right and left atria and the right and left ventricles Atria lie above and behind the ventricles Atrioventricular groove at the surface separates atria and ventricles Interatrial groove separates the atria. Interventricular groove separates the ventricles. Please do not reproduce, redistribute or share without the prior express permission of the author.  Features of the Heart Heart has an apex directed downwards, forwards and to the left. Base or posterior surface directed backwards Anterior or sternocostal surface, formed by the right atrium and right ventricle and partly by the left ventricle and left auricle. Inferior or diaphragmatic surface rests on the central tendon of the diaphragm, formed in its left 2/3 by the left ventricle an in its right 1/3 by the right ventricle. Please do not reproduce, redistribute or share without the prior express permission of the author.  Upper border is slightly oblique and formed by the two atria. Right border is vertical and is formed by the right atrium. Inferior border is horizontal and formed by the right ventricle. Left border is oblique formed by the left ventricle and partly by the left auricle. Please do not reproduce, redistribute or share without the prior express permission of the author.  Chambers of the Heart The right atrium – the right upper chamber of the heart. It receives blood from the whole of the body and pumps it to the right ventricle through the right atrioventricular opening (tricuspid). Please do not reproduce, redistribute or share without the prior express permission of the author.  The right ventricle – a triangular chamber which receives blood from the right atrium and pumps it to the lungs through the pulmonary trunk and pulmonary arteries. Please do not reproduce, redistribute or share without the prior express permission of the author.  The left atrium – a quadrangular chamber, situated posteriorly. It receives oxygenated blood from the lungs through four pulmonary veins and pumps it to the left ventricle through the left atrioventricular (bicuspid / mitral) orifice. Please do not reproduce, redistribute or share without the prior express permission of the author.  The left ventricle – forms the apex of the heart and part of sternocostal surface. It receives oxygenated blood from the left atrium and pumps it into the aorta. Please do not reproduce, redistribute or share without the prior express permission of the author.  VALVES OF THE HEART Valves of the heart maintain unidirectional flow of the blood and prevent regurgitation in the opposite direction There are two pairs of valves in the heart – a pair of atrioventricular valves and a pair of semilunar valves. The right AV valve is called as the tricuspid valve. The left AV is known as bicuspid valve, also called as the mitral valve. The semilunar valves include the aortic and pulmonary valves. The valves are prevented from opening upwards into the atria by tendinous cords, called chordae tendinae, which extends from the inferior surface of cusps to little projections of myocardium covered with endothelium called papillary muscles. Please do not reproduce, redistribute or share without the prior express permission of the author. Please do not reproduce, redistribute or share without the prior express permission of the author. Please do not reproduce, redistribute or share without the prior express permission of the author.  Blood supply to Heart The arterial supply to the heart is provided by the right and left coronary arteries arising from the ascending aorta just above its origin from the left ventricle The right coronary artery supplies the right atrium and ventricles , posterior interventricular septum and the whole of the conducting system of the heart. The left coronary artery supplies left atrium,ventricles,anterior interventricular septum and a part of the AV bundle. Please do not reproduce, redistribute or share without the prior express permission of the author. Please do not reproduce, redistribute or share without the prior express permission of the author.  Conducting system The heart has an intrinsic system of the Heart whereby the cardiac muscle is automatically stimulated to contract without the need of a nerve supply form the brain. However, this system can be controlled by the medullary centres. Please do not reproduce, redistribute or share without the prior express permission of the author.  It consists of specialized cardiac muscle fibres arranged as group of cells (nodes) or bundles of fibres which are responsible for the rhythmic initiation and propagation of the impulse associated with heart beat and the coordinated contraction of the atria and ventricles. Please do not reproduce, redistribute or share without the prior express permission of the author. Please do not reproduce, redistribute or share without the prior express permission of the author.  Nerve supply of the Heart Parasympathetic – vagus (inhibitory) Sympathetic – T3-T5 (acceleratory) Please do not reproduce, redistribute or share without the prior express permission of the author.  Functions of the Heart Blood flows through the heart in a one way system. The right atrium receives deoxygenated blood from the body via the largest vein in the body called the vena cava The contraction of the atrium pumps the blood into the right ventricle and then into the lungs via the pulmonary artery. The blood is oxygenated in the lungs and then returns to the heart and enters the left atrium via the pulmonary vein. Please do not reproduce, redistribute or share without the prior express permission of the author.  The contraction of the left atrium pumps the blood into the left ventricle, which then pumps it to the body via the aorta The wall of the left ventricle is usually much thicker than that of the right ventricle because it has to pump the blood to the end of the digits and tip of the tail while the right ventricle only has to pump the blood to the nearby lungs. Please do not reproduce, redistribute or share without the prior express permission of the author. Please do not reproduce, redistribute or share without the prior express permission of the author. Factors affecting the Heart and Lung Please do not reproduce, redistribute or share without the prior express permission of the author.  The main factors affecting Heart Rate Gender Autonomic nerve activity Age Circulatory hormones, e.g. adrenaline (epinephrine), thyroxine Activity and exercise Temperature The baroreceptor reflex Emotional states Please do not reproduce, redistribute or share without the prior express permission of the author.  Cardiac Output: volume of blood being pumped by the heart, in particularly by a left or right ventricle in the time interval of one minute The main factors affecting cardiac output Cardiac output = stroke volume X Heart rate Factors affecting stroke volume: VEDV (Ventricular end-diastolic volume – preload(ESV)) Venous return Strength of myocardial contraction Blood volume (Systole: Contract; Diastole: Relax) Average Resting HR: 70beats/min Average Resting SV: 70mL/beat Please do not reproduce, redistribute or share without the prior express permission of the author.  Factors determining blood pressure Blood pressure is determined by cardiac output and peripheral resistance. Change in either of these parameters tends to alter systemic blood pressure, although the body’s compensatory mechanisms usually adjust for any significant change. Blood pressure = cardiac output (SV*HR) * peripheral resistance Please do not reproduce, redistribute or share without the prior express permission of the author.  The factors affecting the Lung Elasticity: Elasticity is the term used to describe the ability of the lung to return to its normal shape after each breath. Loss of elasticity of the connective tissue in the lungs necessitates forced expiration and increased effort on inspiration. Compliance: This is a measure of the stretch ability of the lungs, i.e. the effort required to inflate the alveoli. The healthy lung is very compliant, and inflates with very little effort. When compliance is low the effort needed to inflate the lungs is greater than normal, e.g. in some diseases where elasticity is reduced or when insufficient surfactant is present. Note that compliance and elasticity are opposing forces. Please do not reproduce, redistribute or share without the prior express permission of the author.  Airway Resistance: When this is increased, e.g. in bronchoconstriction, more respiratory effort is required to inflate the lungs. Other factors that influence respiration Breathing may be modified by the higher centers in the brain by: Speech, singing Emotional displays, e.g. crying, laughing, fear Drugs, e.g. sedatives, alcohol Sleep. Please do not reproduce, redistribute or share without the prior express permission of the author.  Temperature influences breathing. In fever, respiration is increased due to increased metabolic rate, while in hypothermia it is depressed, as is metabolism. Temporary changes in respiration occur in swallowing, sneezing and coughing. Please do not reproduce, redistribute or share without the prior express permission of the author. Please do not reproduce, redistribute or share without the prior express permission of the author. Q&A Session Please do not reproduce, redistribute or share without the prior express permission of the author.  Thank you Address Telephone Website Lot 33-40, Blok C, Plaza Juta, +6088 431 025/35 kk.cyberjaya.edu.my KM 7.2 Off Jalan Tuaran, 88400 Likas, Kota Kinabalu, Email Sabah, Malaysia [email protected]