CVR Anatomy Year 1 PDF

ANATOMY CVR  Anatomy of the Heart Part 1: Heart Location g Surface anatomy is how we visualize anatomical structures in the thorax by using surface features. We can use: - Palpable landmarks- these can be felt ( eg. Heart is d...

ANATOMY CVR  Anatomy of the Heart Part 1: Heart Location g Surface anatomy is how we visualize anatomical structures in the thorax by using surface features. We can use: - Palpable landmarks- these can be felt ( eg. Heart is deep within sternum). - The sternal angle is the area between the manubrium and the body of the sternum ( also known as manubriosternal junction) What structures lie at the sternal angle? Rib 2 Aortic arch (#5) Tracheal bifurcation (Carina) Pulmonary trunk (#9) Ligamentum arteriosum (fibrous structure that connects between pulmonary trachea and ascending aorta) Azygous vein drains into SVC (drains majority of > Carina - thorax region to SVC) (#7) Nerves (cardiac plexus which is a network of nerves apart of the ANS) ↑ Thoracic duct Others include the pre vertebral and pre tracheal tissue of the neck end and the oesophagus continues past the sternal angle Observable landmarks & Typically associated with muscle - We can see: - Anterior axillary fold ~ Posterior axillary fold - Axillary fossa/Axilla (armpit) - Jugular notch (observable and palpable) Pectoralis major and other muscles Imaginary lines - Lines drawn in the surface for orientation ‘Safe triangle’ are used for procedures like chest drains to make sure error doesn’t occur JOIN THE DARKSIDE - The apex of the heart touches the midclavicular line ↑ Cardiomegaly is when the heart is displaced inferiorly and laterally towards the left side (axilla) & The heart is between vertebral levels of T4-T9 - When supine (laying down): T4/5-T8 & When standing: T6-T9 & The heart is attached to the diaphragm (muscle of respiration) by its pericardium Mediastinum Starts at base of neck and ends right before diaphragm · The thorax is divided into right pleural cavity, left pleural cavity, and mediastinum ↑ Most of the mediastinum is encapsulated by pleural (serous double layered membrane that folds back in itself) g Mediastinum is divided into parts: Inferior, superior, anterior, middle, posterior JOIN THE DARKSIDE  Heart Orientation ↑ Think of the heart like a pyramid (picture shown) and tilt it a little to the left - The base of the heart is actually at the back ↓ The base is made up of the left atrium, part of right atrium, and majority of the great heart vessels - It is difficult to visualize with an ECG because more structure are found at posterior and so the electrode has to penetrate more things making it difficult to see ↓ Inferior surface: in contact with diaphragm ↓ Made up of left ventricle, partly right ventricle, coronary vessels (posterior interventricular groove) Anterior surface: in contact with sternum and ribs - C Front view j It is made up of the right ventricle, partially right atrium, partially G left ventricle, and root of vessels entering and exiting heart right prim Right pulmonary surface: in contact with right pleura and lung surface Mainly in contact with right atrium ↑ Left pulmonary surface: in contact with left pleura and lung Mainly in contact with left ventricle and partially left atrium ↑ Anterior sur face Part 2: Heart Structure Pericardium 3 Layers: I Fibrous- keeps heart in position in thoracic cavity. Attached to phrenic nerve (controls diaphragm) Serous- split into parietal and visceral & Parietal lines the inner surface of fibrous pericardium Visceral forms outer covering of the internal organs (known as epicardium as well) & Pericardial cavity- space between the parietal and serous layers (contains a little bit of fluid). There is about 15-50 ml of fluid to allow for smooth movement of the heart. Clinical Correlation ↑ Pericardial effusion is the buildup of fluid in the pericardial sac Causes include: aortic aneurysms (blood), heart attacks, injuries, inflammation of pericardium (pericarditis) Case: cardiac tamponade - This occurs due to the rapid buildup of fluid that causes pressure and compresses the heart. This can lead ti rapid breathing, shortness of breath, stabbing pains Treatment: pericardial tap (injection syringe to remove fluid) & Sulci/grooves of the heart:structures that separate the ↓ chambers of the heart internally (showed in the external surface). Coronary sulcus: separates atria and ventricles & Interventricular sulcus: separates ventricles (there are posterior - and anterior) JOIN THE DARKSIDE & The right atrium receives venous blood (deoxygenated) from 4 sources: 1. SVC 2. IVC 3. Coronary sinus 4. Anterior cardiac veins (small veins along surface of atrium) ↑ The cardiac skeleton is a complex framework of dense collagen tissue forming four fibrous rings (located in between the atria and ventricles around the AV and semilunar valves) I It provides attachment for the myocardium Made up of : Bicuspid valve Tricuspid valve Aortic ring Pulmonary ring S It acts as an electrical insulator and separates atrial and ventricular contractions AV Valves S Tricuspid- separates right atrium and right ventricle. It has 3 cusps & Bicuspid (mitral)- separates left atrium and left ventricle. It has 2 cusps ↑ The first sound of the heart (LUB) is made by the closing of these 2 valves together Semilunar Valves I Pulmonary- separates right ventricle and pulmonary trunk ↑ Aortic- separates left ventricle and ascending aorta & These valves have 3 crescent shaped cusps. The aortic valve has openings for the left and right coronary arteries Open when ventricles contract. Initially high amount of blood pressure caused the valves to stay open. The ventricles start emptying and valves slowly close. They completely close when there is enough blood that can back flow. ↑ The second sound (DUB) comes from the closure of these valves Valve Abnormalities 1. Stenosis: narrowing of valves (they don’t open properly) 2. Regurgitation: valve is compromised and can’t close properly Can cause heart murmurs and treatment for this is valve replacement surgery Heart Wall Layers Epicardium- outer layer (visceral pericardium, adipose and connective - tissue) Has 2 layers: serous membrane layer & subepicardial layer The serous membrane layer is the outer layer made of mesothelium (simple squamous and cuboidal cells). The subepicardial layer is the inner layer made of connective and fat tissue. Myocardium- middle layer (responsible for contraction and is thicker in & certain areas like the left ventricle wall). It is composed of specialised striated muscle fibres. Myocytes (cardiac muscle cells) are joined at specialized sites called intercalated discs that allow them to function in a coordinated way. The size of the myocardium varies (larger in ventricles). The inside of the myocardium is rough while the outside is smooth. In ventricles it protrudes to folds papillary muscles Endocardium- inner layer (smooth and in contact with circulation blood) - JOIN THE DARKSIDE - Epicardial fat insulates, protects, and supports the heart. It covers about 80% of the heart and is more abundant in the AV and interventricular grooves The endocardium has 3 layers: & Endothelial: flat endothelial cells (innermost layer) Middle: sub endothelial (has collagen fibers) Layer in contact with myocardium: collagen fibres merge with surrounding cardiac muscle fibers (may contain Purkinje fibers). The endocardium is thicker in atria than ventricles Coronary Circulation 2 coronary arteries & Coronary sinus lies on the posterior & Right Coronary Artery Descends vertically between the right atrium and right ventricle ↑ ~ It gives off 4 branches: SA node, right marginal artery, small branch to AV node, posterior interventricular artery (known as posterior descending artery) Left Coronary Artery Divided into 2 branches: anterior interventricular and circumflex ~ branch 1. Anterior interventricular artery continues toward apex of the heart in the anterior interventricular sulcus. It gives off 1 or 2 large diagonal branches 2. Circumflex artery curves around the left and ends just before the posterior interventricular sulcus. This gives off the left marginal artery. - Coronary Dominance Coronary artery distribution depends on the origin of posterior & interventricular artery (PI) In majority of people the RCA supplies a large portion of the posterior wall of left ventricle (right dominance). If the circumflex artery of LCA is the origin and it supplies most of the posterior wall of left ventricle this is left dominance. If it is equal meaning both arteries have equal distribution it is co dominance & SA & AV node supply In SA node it is usually supplied by RCA but for some people it is supplied by LCA ↑ In AV node it is is mainly supplied by RCA and in rare occasions supplied by LCA & Venous Return Coronary sinus receives drainage from great cardiac vein, middle cardiac vein, small cardiac vein, and posterior cardiac vein & The anterior cardiac vein drains directly into the right atrium JOIN THE DARKSIDE ↑ When arteries become obstructed they take arteries from either the leg, thorax, or arm (radial) to replace it. Angiogenesis is creating more branches of a blood vessel for blood flow to damaged areas Wh & ANS nerve fibres can control the rate ofenheartbeats Covered conduction in core (review that)art & eri es be co me ob str uct ed the y tak e art Innervation (control of heart beat) of the Heart eri ANS involved es 1. Parasympathetic (vagus nerve)- slows heart rate. Releases fro acetylcholine and decreases heart rate m 2. Sympathetic- increases heart rate, presynaptic fibers are eit T1-T4, post synaptic are cervical and superior thoracic he ganglia. Releases noradrenaline and increases heart rate r 3. Visceral afferent- linked to referred pain. This is pain felt in the other areas of the body due to miscommunication. It leg occurs because the brain can’t differentiate between , sensory input from visceral sensory neurons in ANS and th spinal nerves from somatic nervous system or ax, or ar m (ra dia l) to re pla ce it. An gio ge ne sis is cr ea tin g JOIN THE DARKSIDE  Anatomy of the Circulatory System Part 1: Circulatory System - This system transports fluids throughout the body ↑ Blood vessels have three layers (tunica): Externa (adventitia): outer connective tissue layer Media: middle smooth muscle (has elastic fibres) Intima: inner endothelial layer - Capillaries don’t have media instead they have pericytes Differences - Arteries have thicker wall as and narrower lumens (hole area). This is because they have elasticity specialization. & Smaller lumens and thick walls help the pressure of blood to keep moving through the system. Arteries also have structures called the Carotid sinus and ↑ Carotid body that act as receptors (baro and chemo receptors). Veins are the opposite and their thickest layer is tunica - externa. The reason for thin walls and thick lumens is because it allows for more blood flow with less vessel resistance. It also allows them to hold more blood without increasing the pressure (70-80% of blood is held in veins) Capillaries only fit 1 blood cell at a time and they are the ↑ ↑ smallest vascular structures in the body. When blood flows through capillaries it is called micro circulation. Main function is to deliver nutrient rich blood to tissues - and take away waste from them. They need to be leaky not allow substances to pass through. ↑ Three types of capillaries: fenestrated, continuous, discontinuous JOIN THE DARKSIDE  Arteries & 2 types of arteries: Elastic- largest type and lots of it in tunica media. It accommodates high pulsatile forces like aorta, p trunk, major branches Muscular- there are only elastic fibres at the intersection of intima and media Ar or media and adventitia. Allows for contraction and relaxation. Dominant in ter most vessels arising from aorta. ies & The arch of the Aorta is the main supply of blood to the head, neck, thorax, 2 and arms. There are 3 major branches: braciophalic, left common carotid, left ty subclavian pe & The descending aorta has many branches that supplies blood to all parts of thes body from the superior aspect. It has the thoracic aorta (above diaphragm) andof Th abdominal aorta (below diaphragm). It passes through the aortic hiatus art e eri de es: sc El en as din tic g - ao lar rta ge ha st s ty ma pe Veins ny an More abundant than arteries br d - Venous return is done with the help of muscle contractions an lot - Vena comitantes: 2 veins that accompany medium/small sizedchdeep s - es arteries. They act as countercurrent heat exchanger (warm arterial of tha blood that warms cooler venous blood before heading back to heart). It it t also forms an arteriovenous pump (arterial blood contraction propels in venous blood). su tu S SVC ppl nic ies Has converging veins: include right/left subclavian, external jugular, a internal jugular veins that from brachiocephalic veins blo me Also azygos veins (drains thorax and viscera in mediastinum) od dia Hemiszygos vein and accessory hemiazygous vein to. It - IVC all ac pa Has veins from all abdominal organs. Includes hepatic portal system. co rts This system drains stomach, intestines and flushes out toxins. It is m formed by the union of superior mesenteric vein, splenic vein atofthe mo transpyloric vein the dat bo es dy hig fro h m pul the sa su tile pe for rio ce r s as lik pe e ct. JOIN THE DARKSIDE It ao  Fetal Circulation 3 vascular shunts that allow for blood to bypass liver and non : functioning lungs 1. Foramen ovale- blood bypasses pulmonary circulation 2. Ductus arteriosus- blood bypasses pulmonary circulation 3. Ductus venous- ensures enough oxygen reaches developing brain The fetus gets its oxygen from the mother via that placenta ↑ circulation. These shunts close post natally Closure of foramen ovale: when a baby takes their first breath this & causes a decrease in pulmonary vasculature resistance. This then increases the pressure in the LA over the RA. This increase in pressure causes it to close. Closure of ductus arteriosus and venosus: there is a decrease in prostaglandins (vasodilator that keeps the ducts open). Bradykinin is a substance that is released from the lungs because of an increase in O2. This causes the walls of the ducts to contract and close. Lymphatic System Lymphatic return: 1. Fluid leaves capillaries and enters interstitial space 2. The fluid enters the lymphatic system by lymphatic capillaries and they form lymphatic vessels 3. lymph passes through many lymph nodes before draining into lymphatic trunks Lymphatic Drainage & Cisterna chyli: dilated origin of thoracic duct that receives fatty lymph from intestine before it drains into thoracic duct. Thoracic duct Right lymphatic duct The left atrium and ventricle drain into the right subclavian junction & The right atrium and ventricle drain into the left subclavian junction - Part 2: Major Vessels Aorta 1. Ascending aorta 2. right and left coronary arteries 3. Aortic arch 4. Brachiocephalic artery 5. Branches to right subclavian (supplies right upper limb and some head and neck) and common carotid artery (supplies right had and neck) 6. Left common and subclavian artery 7. Descending thoracic aorta Venae cavae (SVC) 1. Formed from the right brachiocephalic vein 2. That is formed from the right internal jugular (drains right head and neck) and subclavian vein (drains right upper limb). Right lymphatic duct drains close to this vein 3. Same with left brachiocephalic vein except the thoracic duct drains at the V formation of this being JOIN THE DARKSIDE & The azygous vein enters the SVC right before it drains into the right atrium Pulmonary Trunk Divides at arch of aorta into right and left pulmonary & artery - They both divide into 2 others at the hilum of each lung Pulmonary Veins 2 pulmonary veins leave from each hilum of the lung - and enter either side of left atrium JOIN THE DARKSIDE  Anatomy of the Respiratory System Part 1: The Thoracic Cage (Rib Cage) & Made up of 3 parts: Sternum, ribs, thoracic vertebrae - Function: provide structure and protection S It’s important to note that it is flexible to allow lungs to expand Sternum (breastbone) & Helps protect internal thoracic viscera - Made up of 3 parts: manubrium, body, xiphoid process ↓ The sternal angle (angle of Louis) is the area between the manubrium and body (found at T4 vertebral level) Sternoclavicular joints: formed by the connection of large fossa on both - sides of jugular notch and ends of clavicles. The costal cartilage of the first rib attaches to a facet on the ~ manubrium while the second costal cartilage attaches to a demifacet on the sternal angle. For ribs 3-6 there are facets and for 7 there is a demifacet on the - xiphoid process. The xiphoid process is the small bottom part of the breastbone. It can - be different shapes and sizes. The tip is usually at vertebral level T10. When we are younger it’s made if cartilage but as we grow older in turns into bone. The Ribs - Articulate posteriorly Protect internal organs - True Ribs: interact with sternum with their own costal cartilages (1-7) & False Ribs: don’t interact with sternum using their own costal cartilages & rather use the costal cartilage above them (8-10)Pa & Floating Ribs: not attached to sternum at all or have rt any costal - cartilage (11-12) 1: Ribs can be classified as typical (generalized structure) Th or atypical (variations) e & Typical Ribs have a head, neck, and body (shaft).ThThe head has 2 articulated facets separated by a wedge of bone.orThe lower facet interacts with the corresponding vertebrae while the aci upper one interacts with the vertebrae above. The body of the rib is flat c and curved, the internal surface of it has a groove (costal groove)Cathat protects the blood vessels and nerves. There is something called ge a tubercule (a bump) that connects to the transverse process of(Rithe corresponding & vertebrae. b Atypical Ribs (1,2,10,11,12) are all different Ca Rib 1- shorter and wider and only has one facet ge) for attachment Rib 2- thinner and longer than rib 1 and has a roughened M area on upper surface ad Rib 10- only one facet e Rib. 11 & 12- only interact with bodies of their own up vertebrae, no tubercles or necks of & The Thoracic Vertebrae 3 12 of them that are medium sized and increase inpasize as we go down the body. Their function is to interact with ribs rts : St er nu JOIN THE DARKSIDE - Each T vertebrae has 2 Demi facets that interact with the heads of 2 different ribs Example: Rib 2 interacts with bottom demifacet of T1 and top demifacet of T2 On the transverse processes of T vertebrae there is a transverse ~ costal facet for interaction with body of a single rib Example: Rib 2 interacts with costal facets of T2 G y Each rib forms 2 joints: ⑧ Costovertebral joint: between head of rib and superior costal facet of ↑ corresponding vertebrae, and inferior costal facet of vertebrae above. Costotransverse joint: between tubercle of rib and transverse process - of corresponding vertebrae. Part 2: The Respiratory Tract Upper- nose, nasal passages, paranasal sinuses, pharynx, portion of & larynx above the vocal cords Lower- larynx below vocal cords, trachea, bronchi, bronchioles and / lungs On the lateral wall of each nostril there are 3 bones called conchae. ↑ B On both left and right side there is superior, middle, and inferior nasal / conchae (turbinate bones). There function is to increase surface area and allow warm air to travel & down the lungs. & The oral cavity is bordered by a hard palate and soft palate. The soft palate ends ends at a region called the uvula The pharynx is divided into 3 parts: - Nasopharynx: posterior to nasal cavities and above soft palate - - Oropharynx: posterior to oral cavity and superior to upper part of epiglottis Laryngopharynx: extends from superior part of epiglottis to top of - esophagus & Trachiobronchial tree: trachea, bronchi, and bronchioles Larynx—> trachea—> lungs ↑ The trachea runs from lower border of the cricoid cartilage to T4 vertebral level. It then splits into left and right primary bronchi. The C rings of trachea are made of hyaline cartilage that are held together by dense connective tissue. The trachea is covered in smooth muscle S (trachealis muscle) The carina is a ridge between the left and right bronchi. By looking at the carina we can determine conditions. Example: widening of carina can indicate cancer of lymph nodes called inferior tracheobronchial lymph nodes. It is more likely for something to be stuck in the RMB because it is sort of directly under the trachea : The RMB is wider, shorter and lies at a steep vertical angle The LMB is narrower and more horizontal These 2 main bronchi divide into secondary (lobar) bronchi; 2 on the & left and 3 on the right. The secondary bronchi divide further into tertiary (segmental) bronchi (10 per lung) JOIN THE DARKSIDE & Tertiary gives rise to terminal bronchioles (don’t have hyaline cartilage in their walls. Respiratory bronchioles branch from terminal bronchioles and each one ends in an acinus of clustered alveoli Histology & Pseudostratified columnar ciliated epithelium: lines the majority of the respiratory tree from nasal cavity to bronchi Simple columnar/simple cuboidal epithelium: lines bronchioles as tube gets - narrower & Simple squamous epithelium: lines alveoli & Pseudostratified columnar epithelium: found in trachea and bronchi The Alveoli Alveolar walls have different structure to bronchioles (no cilia or smooth & muscle) It is lined by thin simple squamous epithelial cells- pneumocytes & Type 1- responsible for gas exchange - Type 2- secrete substance caked surfactant (reduces surface tension in & alveoli keeping them open and prevents sticking) Surfactant & Premature Babies Surfactant is a mixture of fats and proteins that prevents alveoli from & sticking together. Its production begins at 24-28 weeks and most babies have enough by 34 weeks. Premature babies won’t have enough and this can cause Respiratory Distress Syndrome (RDS) Part 3: The Lungs The Pleura > Parietal pleura lines internal surface of thoracic cavity. It is named differently depending on the area its lining: & - Diaphragmatic parietal pleura: lines superior surface of diaphragm Mediastinal parietal pleura: lines lateral surface of mediastinum Costal parietal pleura: lines internal surface of ribs - Cervical parietal pleura: extends above rib 1 to root of neck - Hilum= located on medial aspect of each lung. This is where the bronchi, S & arteries, veins & nerves enter/exit the lung The lung can be split into 10 parts that have their own artery and are independent (so in surgery one part can be removed without - affecting other parts) Pulmonary arteries deliver blood to capillaries around the alveoli where gas S exchange takes place and pulmonary veins return blood back to the heart S Common carotids- take blood to head and neck & Subclavians- take blood to upper limbs Descending aorta- transports blood to thorax, abdo/pelvis, and lower & limbs - Trachea and bronchial tree get blood directly from thoracic aorta Bronchial arteries branch from thoracic aorta or sometimes from posterior intercostal arteries JOIN THE DARKSIDE  Vasculature & Trachea and bronchial tree are drained slightly different routes on the left and right side & Left side- bronchial veins drain into the accessory hemiazygos vein that drains into the azygos (on right) into the SVC Right side- bronchial veins drain into azygos vein & Diaphragm Has 2 dome-shaped parts and is made of mostly muscle around the & edges. These muscle fibres come together in the middle to form a strong, flat area called the central tendon The Phrenic nerve (located from C3, C4, C5) controls the diaphragm ↑ Has 3 areas of attachment: ↑ 1. Costal cartilages and inner surface of ribs 7-12 2. Lumbar vertebrae and associated discs 3. Xiphoid process Respiratory Movements 1. Anteroposterior- front of chest lifts 2. Transverse- ribs move up and out of their joints (lifting both handles of a bucket) 3. Vertical- diaphragm moves down creating more space for chest & IVC PASSES THROUGH T8 LEVEL ESOPHAGUS PASSES THROUGH T10 LEVEL & AORTA PASSES THROUGH T12 LEVEL & Part 4: Muscles of the Thoracic Wall & We have internal and external intercostal muscles S External intercostal muscle- outer layer, runs from inferior border of one rib to superior border of rib below, goes in hands in pocket direction Internal Intercostal muscle- middle layer, runs from superior border of one - rib to inferior border of rib above, only function is forced exhalation, hands on chest direction - Innermost intercostal muscle- deepest layer, separated from the other 2 by neurovascular bundle, same function as internal JOIN THE DARKSIDE