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20 Cards in this Set
- Front
- Back
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Heart chambers
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Right atrium - recieves blood from the superior and inferior vena cavae, and the coronary sinus
Right ventricle - recieves blood from the right atrium through the tricuspid valve. Blood leaves here via the main pulmonary artery through the pulmonary semilunar valve. The left atrium drains the pulmonary veins. Blood flows out through the mitral valve to the left ventricle. The left ventricle expels blood to the body via the aorta through the aortic (tricuspid) valve. |
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The right atrium
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Recieves blood from the superior and inferior vena cavae and coronary sinus.
Parts: Sinus venarum - The smooth surface posteriorly surrounding the SVC and IVC openings. Originates fromt he seperate (from the heart) sinus venosis, which is integrated into the atrium. Right atrial body - The bulk of the atrium, seperated from the sinus venarum by the crista terminalis. The line anchors the pectinate muscles, which run around the atrium in the coronal plane giving it a trabeculated appearance. Right atrial appendage - Arising from the anterosuperior area of the atrium, this small muscular pouch containing pectinate muscle projects left and up, towrds the aortic root. Landmarks Coronary sinus orifice - posteriorly in the atrium to the left of the IVC and just superior to the leaflets of the tricuspid valve. The sinus itself runs transversely along the atrioventricular groove There is a pseudovalve of the coronary sinus called the coronary valve or Thebesian valve. The orifice of the inferior vena cava - low on the sinus venarum, right lateral in the atrium, the opening is ringed by the valve of the IVC, or the Eustachian valve, which is a remanent from the fetal circulation, which directed blood through the foramen ovale. The Eustachian valve, the Thebesian valve and the medial (septal) cusp of the tricuspid valve are the boundaries of the triangle of Koch. The atrioventricular node sits in the middle of this triangle. The orifice of the superior vena cava - the opening is superior and right lateral in the atrium, in the region called the sinus venarum. The inta-atrial septum - the medial wall of the atrium, seperating it from the left atrium The fossa ovalis - the remnant of the foramen ovale, the opening between the atria in utero. This fails to close in 20% of people, but is symptomatic in far less than this. The ridge around the fossa, most prominent superiorly is called the limbus of the fossa ovalis. The anterior wall - though there are no named openings, the 3 or 4 anterior cardiac veins drain into the anterior wall of the right atrium. |
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The right ventricle
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Similar volume to the left ventricle (~85ml) but the muscle is ~1/3 the thickness.
Parts: The tricuspid valve - The valve between the right atrium and ventricle, made of three leaflets, operated by 3 papillary muscles. The papillary muscles are attached by the chordae tendinae The pulmonary valve - the semilunar valve between the right ventricle and pulmonary trunk. There are no chordae tendinae in semilunar valves, which function similar to to venous valves in the legs. The body - triangular in form, thicker muscled at the base and thinner at the apex, runs from the right atrium to the apex of the heart. Landmarks: Ventricular septum - the posterior wall, which bulges into the right ventricle, forms the border between the left and right ventricles. Thickly muscled. Papillary muscles - there are 3 papillary muscles in the right ventricle, anchored toward the apex in anterior, posterior and septal locations. They are connected to the 3 leaflets of the tricuspid valve by the chordae tendinae. Conus arteriosus - The infundibular dilatation superiorly and left in the ventricle which opens into the pulmonary trunk. The septomarginal trabecula - a ridge running from the anterior papillary muscle to the septum carries (as a shortcut) part of the right bundle branch of conduction to the papillary muscle, allowing co-ordinated papillary muscle action. |
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The left atrium
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Recieves blood from the four pulmonary veins, and outputs blood through the mitral valve to the left ventricle.
Parts: Left atrial appendage - a long trabeculated pouch that extends up and anterior on the suerior left of the atrium. Inflow portion - smooth, contains openings for (usually) 4 pumonary veins Landmarks: ... seems pretty featureless. Only the appendage has pectinate muscles, the atrium proper is smooth. |
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The left ventricle
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Thickly muscled, the majot outflow tract of the heart.
Parts: The mitral valve - The aortic valve - The body - contains fine trabeculae carnae Landmarks: not much to see here either ... Papillary muscles - 2, 1 for each cusp of the mitral valve (anteromedial and posterolateral) |
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The mitral valve
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a
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The tricuspid valve
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a
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The conduction system of the heart
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a
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Pulmonary veins
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Return oxygenated blood from pulmonary capillaries to the left atrium.
Normally there are 2 pairs of superior and inferior veins (total of 4) but with frequent variation. The pulmonary venous tree does not follow the branching path of the bronchioles or arteries, but instead drains fairly directly inward, crossing lobes and segments. The divisions large enough to be named are the: Superior pulmonary veins which drain the upper and middle lobes (the middle lobe vein is often named as well) Inferior pulmonary veins which drain the lower lobes Variation: 70% have 4 main pulmonary veins. Variations otherwise are underincorporation of vessels into atrium (ie a main trunk and only 1 vessel entering the atrium on that side) in 12-25% or overincorporation resulting in supranumery or additional veins entering the atrium. Normally this would be a middle lobe vein, which occurs in 17-23%. The other variation can be where the middle lobe vein goes. As stated, it can enter the atrium in 17=23%. It usually joins the superior pulmonary vein (50-70%) but very occasionally joins the inferior pulmonary vein (3-8%). Other venous anomolies include: a vertical upper lobe vein draining to the brachiocephalic on the left Scimitar syndrome where some anomolous drainage of the right lung is into the IVC, hepatic or portal veins. This creates a very short blood loop and is associated with right pulmonary hypoplasia. |
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Pulmonary structures - A,V, L
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a: follow bronchi - anterior on the right and posterior on the left (the left pulmonary artery curls superiorly over the left main bronchus)
v: drain centrally, cross lobes l: follow bronchi, nodes usually form at bronchial bifurcations (confluence on efferent channels) |
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Pulmonary fissural variants
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Azygos fissure -
Failed migration of the aygos vein along brachiocephalic to tracheobronchial angle. 10-20% Left minor fissure - Fissure around lingula 10-20% Superior accessory fissure - seperates apical segments of lower lobes (looks like smaller horizontal fissue) Inferior (cardiac) accessory fissure - Seperates medialbasal segments, more common on right than left. 15-20% CT studies. MISSING/INCOMPLETE FISSURES: The normal fissures are incomplete in 20-90% of cases, more common on the right than left, and more common in the minor fissure than the major fissures. |
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Mediastinum
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Coronary arteries
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The right and left main coronary arteries arise from the corresponding (right and left) aortic coronary sinuses of Valsalva. There is also a posterior aortic sinus that usually nothing arises from.
LEFT CORONARY ARTERY: Passes leftwards from the sinus, behind the pulmonary trunk and bifurcates into LAD and LCX Left anterior descending: Runs in the interventricular groove and terminates adjacent to the cardiac apex.It gives off anterior branches (called septal branches) and posterior branches (called diagonal branches) supplying the anterior septum and anterior wall of LV respectively. Left circumflex artery: Runs in the left coronary sulcus along the left cardiac border and posteriorly. It gives of obtuse marginal branches anteriorly, which supply the lateral LV. RIGHT CORONARY ARTERY: The right coronary arises from the sinus and runs rightward and down in the right coronary sulcus. It wraps around to the middle of the posterior surface of the heart. Branches: conus branch to the pulmonary trunk, sinus node artery posteriorly anterior branches to the right ventricle Acute Marginal Artery which runs to the apex along the inferior border of the heart, supplying the free wall of the right ventricle Posterolateral Artery which is the terminal branch and runs to the mid posterior heart after the Posterior Descending Artery branches off, running downward in the posterior interventricular septum. Together these 2 branches supply the posterior heart wall. V: LCA branch - ramus intermedius between the LAD and LCX, to anterior left ventricle. Sinus node artery arises from LCX in 40% DOMINANCE: 85% are right dominant, meaning the RCA supplies the PDA and PLA 7.5% are left dominant - LCX supplies PDA and PLA 7.5% are co-dominant - LCX to PLA, RCA to PDA |
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Coronary artery territories
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The myocardium can be seperated into clear vascular territories.
These territories are supplied by the 3 major vessels - left anterior descending left circumflex (off LAD) right coronary The below rule is accurate in 85% of people, with right coronary dominance (which means the RCA supplies the posterior arteries - the posterior descending and the posterolateral arteries) If you divide the heart into 3rds circumferentially, then it is fair to say the left anterior third is the LAD, the right third is the RCA and the posterior left third is the LCX. At the apex the LAD takes over a little more, to supply the left anterior 1/2 of the heart, with the remaining 2 arteries evenly supplying the remainder. |
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Cardiac veins
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All drain to the large coronary sinus on the posterior heart, to drain into the right atrium.
The great cardiac vein starts at the apex, runs along the LAD before turning along the LCX to finish in the coronary sinus. The small cardiac vein starts on the lower right border of the heart to run along the RCA and PLA to the coronary sinus. The middle cardiac vein runs from the posterior apex along the interventricular groove with the PDA to the coronary sinus. The oblique cardiac vein runs from the left atrium to the coronary sinus (no artery adjacent - it is actually a remnant of the left sided SVC) The posterior vein of the left ventricle runs along the posterior LV to the sinus (no artery) Seperately, the anterior cardiac veins drain the RV and RA anteriorly, and drain straight into the RA. |
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Pericardium
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The sac like membrane that surrounds the heart and proximal great vessels.
Sits in the anatomic middle mediastinum. The capsule is bound by ligaments to the diaphragm, sternum and is continuous with the pretracheal fascia. There is a fibrous capsule, with a parietal pericardial layer adhered to this. There is also a visceral layer which is adhered to the heart. Between these 2 layers is 15-50mL of pericardial fluid. The anatomy of the pericardium can be seperated into the pericardial space, its innervation and blood supply: PERICARDIAL SPACE: The space is invaginated by 2 reflections, the first around the aorta and pulmonary trunk and the second around the SVC/IVC and pulmonary veins. The first is a straight horizontal tube, and the second a Y-shaped structure, slightly oblique from left-superior to right-inferior. Between these there are 2 spaces where the pericardial space is expanded. The transverse sinus between the tubes and the oblique sinus beneath the lower (SVC/IVC/PV) tube, behind the left atrium. The sinuses are seen on CT and MRI as areas of tissue and fat density in between posterior cardiac/vascular strucutures. The reflections form several small recesses In the transverse sinus: the right and left pulmonic recesses laterally and the superior aortic recess cranially Adjacent to the oblique sinus: These reflections are outside the oblique sinus, formed by lateral reflections around the pulmonary veins and SVC/IVC - the bilateral pulmonary venous recesses between the superior and inferior pulmonary veins - the postcaval recess between the SVC and superior right pumonary vein. Because the sinuses and recesses contain pericardial fluid they can mimic pathology/lymoh nodes/cysts. NEUROVASC: Vagus and phrenic nerves supply parietal pericardium. Dermatome is top of shoulder/supraclavicular region Internal thoracic arteries (from subclavian) and thoracic aorta supply the pericardium blood. The aortic branches are the coronary arteries superiorly and the superior phrenic arteries inferiorly. Venous drainage is by the azygos and internal thoracic veins. |
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Thoracic aorta
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3 parts: Ascending, arch, descending
ASCENDING: Originates at the orifice of the left ventricle - parts are the aortic annulus (valve), the aortic sinus of valsalva (the bulge) and the sino-aortic junction (the end of the sinus. The sinus of Valsalva has left, right and posterior portions. The left and right coronary arteries arise in the left and right portions. The posterior portion is kind of bare. AORTIC ARCH: Curls over posteriorly and to the left. Apex is on the left side of the trachea. It ascends anterior to the trachea and left pulmonary artery, curls over the left hilum and descends behind it. Branches: Brachiocephalic (to the right) Left common carotid Left subclavian The ligamentum arteriosum is below the aortic arch, running between it and the main pulmonary trunk. It is the closed remnant of the ductus arteriosus, which closes after birth. DESCENDING AORTA: Descends on the left of the midline, passes through the diaphragm at the aortic hiatus posteriorly. Gives off bronchial arteries to the hilar bilaterally, posterior intercostal arteries and small branches to the mediastinum, oesophagus. Lower are the subcostal and superior phrenic branches, just above the diaphragm. VARIATION: Bovine arch in 20% - LCCA arises from brachiocephalic, not arch Aberrent right subclavian 0.5-2.5% - the right subclavian arises from the arch, usually last (after the left subclavian) and passes posteriorly, usually behind trachea and oesophagus. Can cause dyspneoa and dysphagia. Arch origin of left vertebral in 10% Right aortic arch in 0.1 - 0.2% - arch is reversed in orientation, associated with congential heart disease Double aortic arch in up to 0.3%, bilateral arches that give off branches to their respective sides, and join behind trachea to form the descending aorta (a vascular ring). Can compress the trachea/oesophagus. |
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Systemic venous drainage n the chest
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There are 2 venous drainage systems in the chest, which communicate with each other but can be viewed seperately.
The azygos system and the vena cavae VENA CAVAE: The superior vena cava returns blood from the right and left brachiocephalic veins and the asygos vein to the right atrium. Ignoring the azygos, the remaining drainage of the SVC includes the head, neck, bilateral arms and upper 3 posterior intercostal veins on the left (these vessels arise from the subclavian (1) and the brachiocephalic (2,3). The IVC drains the abdomen, including all organs, the legs and abdominal walls. The azygos system drains the remaining intercostal spaces. AZYGOS: There are bilateral tributaries , called the azygos on the right and hemiazygos on the left, originating from the IVC and left renal vein/left ascending lumbar vein respectively. There is a lot of variation of origin. The aygos runs along the right side of the vertebral column from T12 to around T4, where it arches forward over the right main bronchus to drain into the SVC. It gives off branches along all posterior intercostal spaces except the first (which comes off the right brachiocephalic). The braches to 2,3 and 4 come off a single trunk, the superior intercostal vein. The hemiazygos runs partially up along the left side of the vertebral column, from T12 to T9, draining the posterior intercostal veins of these levels. At T9 it crosses the midline and drains into the azygos vein. Above this at around T8, the azygos vein gives a branch off left, which is called the accessory hemiazygos, and drains T4-T8 intercostals. All together the accessory hemiazygos and hemiazygos drain T4-T12 intercostal spaces, returninf blood to the azygos vein. The upper 3 left intercostal spaces are drained by the superior left intercostal vein, which returns blood to the left brachiocephalic vein. VARIANTS: Persistent left SVC in 1-3% : Normally disappears early in development. Runs from confluence of subclavian and IJV to coronary sinus usually. Azygos continuation of IVC: The IVC can terminate in the liver, with a large azygos continuing into the abdomen instead. |
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Thoracic duct
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Runs from the confluence of abdominal lymph channels (the largest being the lumbar trunks) adjacent the renal veins (the cysterna chyli), on the right side.
Ascends to the thoracic cavity via the aortic hiatus. It ascends along the anterior region of the vertebral column. It crosses to the left between T4 and T6. Runs along the left verterbal border and curls behind the confluence of the left subclavian and left IJV to drain. It often recieves subclavian and jugular lympahtic trunks in the terminal portion. |
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Thymus
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