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Neck Anatomy Sections: CT & MRI · Acedra
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Neck Anatomy Sections: CT & MRI
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0:03
I'm going to use anatomical sections as well as CT sections, axial sections. The anatomical sections are arranged to match the CT and MRI sections in other words they are arranged as if looking at the body from below so this will be the right side of the body and this will be the left side of the body the anatomical sections are selected from the visible human project this section is at the
0:33
root of the neck, in general, we can see here the shoulder this is the humerus, the scapula here's the coracoid process of the scapula and this is the glenoid cavity. This is the posterior side this is a vertebra, vertebral body, a spinous process, and the spinal cord inside. Anteriorly we can see evidence of the clavicle here and pectoral muscles, sternomastoid muscle, and in the midline, this is the trachea where you can see some of the rings tracheal rings the C-shaped rings.
1:11
Behind the trachea and related to the vertebral body is the esophagus. At the root of the neck, we can see the apex of the lung so this is the field of the apex of the left lung and this is the field of the apex of the right lung because the lung extends about two centimeter two to four centimeter even up above the medial end of the clavicle but it does not extend above the head of the first rib. Here we can see evidence of the ribs for example here, here,
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and there there are ribs. This is because of the fact that the ribs are obliquely set in the superior thoracic aperture, this is, for example, this is the vertebral body is located here and the rib is set obliquely and so the apex of the lung while extending above the level of the rib and above the level of the clavicle it does not extend above the level of the head of the rib although it
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extends above the level of the anterior end of the rib and the clavicle. Also in this section, we can see the internal jugular vein. this is the internal jugular vein here and there the right and left internal jugular veins. Now, the next section is going to pass it through this level at the root of the neck and we can see here that this section will pass through the clavicle and will pass through the subclavian vein as well here is the subclavian vein and it
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will show its union with the internal jugular vein to form the brachiocephalic veins on both sides. of course, the section will also pass through the trachea here and the esophagus behind it so let's look at the section here again we can see anteriorly is the medial end of the clavicle is located here and these are the pectoral muscles pectoralis major arising from the clavicle and posteriorly is the vertebral body and this is a costovertebral joint a transverse process of
3:42
a vertebra and a vertebral canal containing the spinal cord here this is evidence of an intervertebral disc cartilaginous intervertebral disc on either side we can see the lung on the left and on the right. In the midline there is the esophagus related to the vertebral bodies and anterior to that is the trachea you can see that the trachea is flattened posteriorly because the trachea has a skeleton which is made of a cartilage this whitish part but these
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cartilages are C-shaped cartridges and they are deficient posteriorly where they are connected by the trachealis muscle so it is a flattened posteriorly where it is related to the esophagus
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and here we can see the subclavian vein on either side the subclavian vein is horizontal and then it unites with the internal jugular vein you can see here this rounded profile of the section of the internal jugular vein they meet together and they form the brachiocephalic veins also we can see that around the trachea there are three main arteries these are the branches of the arch of the aorta on the right side it's the brachiocephalic trunk and on the
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left side it is the common carotid artery and the subclavian artery. In the thoracic wall, we can see evidence of ribs this is a rib, here another rib, here another up there so we can see multiple sections of ribs this is because the ribs are set obliquely so in one horizontal section like this one you can see multiple profiles of ribs because they are set obliquely so multiple profiles can be seen in one section and in between the ribs there are intercostal muscles
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so this is an intercostal space containing intercostal muscles here again you can see intercostal muscles and outside that is a muscle here this is the serratus anterior muscle you can see that attachment of serratus anterior it's attached here it's attached to the medial border of the scapula actually it's attached to the anterior aspect of the medial border of the scapula and goes around the thoracic wall. In the next section, we are going a little bit
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lower down and so we can see the brachiocephalic veins, in the previous section we have seen the union of the subclavian and the internal jugular vein. in the section before that, we have seen only the internal jugular vein then the internal jugular and the subclavian veins and then in the next section we will see it's a lower down section so we can see the brachiocephalic veins. An important point here about the brachiocephalic veins is that you can
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see that there is a left brachiocephalic vein which is longer and it is set obliquely and a right brachiocephalic vein which is shorter and is more vertical than the left brachiocephalic vein so in a horizontal section the profile of the right brachiocephalic vein will be more or less circular while that of the left brachiocephalic vein will become more or less oval in n section because it is set more horizontal than the right brachiocephalic vein; so here we are, in this
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section we can see the left brachiocephalic vein it looks oval because it is more oblique than the vertical right brachiocephalic which is circular in profile you can see here that the veins are the most anterior structures here in the superior mediastinum we can see them here again they are the most anterior structure behind the veins and in the same section are the arteries the arteries which are the three branches of the arch of the aorta so we can see them here this is the
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brachiocephalic trunk and then the left common carotid and the left subclavian arteries we can see that these arteries they are spiraling around the trachea and esophagus this is the trachea and here is the esophagus is most posterior against the vertebral body also I want you to notice that these arteries as we go down they will come close to each other because they arise from the same
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origin and as we go higher they will go away from each other so for example if we go back a little bit higher I want you to notice these arteries right now and note how these arteries look like when we go a little bit higher so here again you can see that the arteries are located far away from each other they are far away from each other because as they go up they will spread apart again
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we can see the lungs here this is the left leg and the right lung and the ribs, intercostal muscles, serratus anterior muscle, and the other features that we have seen the costal vertebral joint and a Costotransverse joint here the spinal cord is very clear and this is a spinous process of a vertebra this section anteriorly, it shows the sternum and it shows the medial end of the clavicle where the
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clavicle articulates with the sternum at and this is a synovial joint and you can see the hyaline cartilage at either side of the joint but in within the joint space there is another cartilage a fibrocartilage this is an intra articular cartilage which is a characteristic of the sternoclavicular joint so this is this section is at the level of the sternoclavicular joint also we can see here evidence of a costal cartilage and this is the first costal cartilage which
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is located just beneath the clavicle so the first costal cartilage that is going again to articulate with the manubrium of the sternum again take a look at the structures in the superior mediastinum the most anterior are the veins and then they are followed by the arteries the branches of the arch of the aorta then the trachea and then the esophagus now this is an axial CT which is almost
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at the same level of the previous section, almost at the same level so let's look at the structures here anteriorly we have the sternum and here these are the ribs posteriorly is a vertebral body and anterior to the vertebral body is the esophagus anterior to it is the trachea and then we can see the vessels here the three vessels arteries this is the brachiocephalic trunk, left common carotid and left subclavian arteries and then more anteriorly we can see the veins this
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is the brachiocephalic vein this one and this one the left brachiocephalic vein as I said it's more horizontal so in section it looks oval while the right brachiocephalic vein is rounded in section because it is more vertical so I want you to compare these features at least in the midline with the anatomical section veins, brachiocephalic vein, arteries, trachea, and esophagus and here the brachiocephalic veins, arteries, trachea, and esophagus.
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Now this is another section a little bit lower down where we can see here the sternum anteriorly and a costal cartilage, first costal cartilage and then behind the sternum are the brachiocephalic veins you can see here that the left brachiocephalic vein is approaching the right brachiocephalic vein let's compare their position in the previous section this is the position higher up the left brachiocephalic vein then it will
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approach the right brachiocephalic vein so it is approaching the right brachiocephalic vein; posteriorly, again, we can see the arteries the three arteries the brachiocephalic trunk the left common carotid the left subclavian arteries now they are so close together because they are approaching their origin from the arch of the aorta again as I mentioned that these arteries as we go higher up they will spread apart from each other so look take a look at
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them again they are very close to each other here now they are a little bit away from each other and now they are much further away from from each other this is the brachiocephalic trunk left common carotid and left subclavian arteries. Then we have the trachea and the esophagus, again on each side of the mediastinum is a lung which is enclosed by the pleural cavities. Pectoral muscles, here is pectoralis major and deep - it is pectoralis minor muscle is shown.
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This is a CT section almost at the same level as the anatomical section so we can see here the left brachiocephalic vein approaching the right brachiocephalic vein to form the superior vena cava behind the veins are the three arteries the brachiocephalic trunk, left common carotid, and left subclavian arteries and then we have the trachea and the esophagus again we can see pectoralis major anteriorly and deep to is pectoralis minor muscle.
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Multiple profiles of ribs are seen because of their obliquity and in between the ribs are intercostal muscles and these are the lung fields right lung field and the left lung field. The level of the next section will be a little bit lower down it will pass through the superior vena cava and at the same time it will pass through the level of the upper part of the arch of the aorta so we will see the superior vena cava and the arch
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of the aorta we will no more see the branches of the arch of the aorta because the branches of the arch of the aorta can be seen at a level a little bit higher than this level. So this is the section passing through the superior vena cava we can see the superior vena cava it has just been formed there is a remaining part of the left brachiocephalic vein and this is the superior vena cava completely it's vertical and this is witnessed by the circular
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profile here and the union is taking place at the level of the first costal cartilage attached to the sternum here again we can see that the vein is the most anterior of the structures the only thing that's anterior to it here is a remnant of the thymus gland and on the left side is the arch of the aorta you can see that the arch of the aorta is touching the trachea, the left side of the trachea here and so it pushes the lower part of the trachea a
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little bit to the right and also it touches the esophagus so again thymus, brachiocephalic vein, left brachiocephalic vein ending into the superior vena cava the on the left side is the arch of the aorta then the trachea and the esophagus and here we can see the vertebral body, vertebral canal containing the spinal cord and the lung fields on either side. This section is almost at the same level it's a CT an axial CT almost at the same level of
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the anatomical section so here's the sternum here and this is the superior vena cava on the right side and the arch of the aorta heading toward the left side and here is the trachea and behind it is the esophagus. A vertebral body, costovertebral joint, transverse process, another transverse process and costotransverse joint with the tubercle of a rib. This is a spinous process and the vertebral canal and of course, this is the scapula can be seen here.
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Now this section is almost at the level of the transverse thoracic plane that is to say the level of the lower border of the T4 vertebra it is also at the level of the manubriosternal joint, the sternal angle. There are many relations taking place at this plane but of course, we cannot see all these relations in only one section what we are going to see right now is a section that passes at the level of the arch of the azygos vein this is the azygos vein coming
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from behind forwards on the right side and it will meet the superior vena cava, so this is what is seen in the section this is the superior vena cava here and the azygos vein now draining into the superior vena cava this is on the right side the azygos vein coming from behind forward forming an arch above the root of the right lung look at the superior vena cava here and let's go up this is again the superior vena cava at the site of its formation at the level of its formation
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and if I go a little bit up this is the right brachiocephalic vein and left brachiocephalic vein they have not joined together to form the superior vena cava. The superior vena cavae forms at the level of the first costal cartilage right first costal cartilage and at the level of the transverse thoracic plane it receives the azygos, arch of the azygos vein also at this level we will not be able to see the arch of the aorta but we will be able to see the ascending aorta and the
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descending aorta. If we go a little bit up we are going to see the arch of the aorta; so at one level of the section here, for example, where we see the ascending aorta then we can see the descending aorta if we go a little bit up we will see the arch of the aorta as an oval structure and if we go a little bit up then we will no more be able to see the arch of the aorta but the branches that arise from the arch of the aorta. So here are the branches of the arch of the aorta at a
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higher level section and here is the arch of the aorta at a lower level section further down is the ascending and the descending aorta also at this section we can see the trachea and we can see that the trachea is starting to bifurcate actually, so it's widening and behind it is the esophagus. Most anteriorly on the side of the sternum, we can see the artery, the internal thoracic artery.
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This is a CT section almost at the same level as the anatomical section that we have just seen, so we can see the ascending aorta, the descending aorta on the left side; this is the trachea behind it is the esophagus and this is the superior vena cava on the right side and you can see that the superior vena cava is receiving the arch of the azygos vein. In the next section, we're going to see the pulmonary trunk arising from the infundibulum of
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the right ventricle so here again we can see the aorta we have just seen the ascending aorta and descending aorta these are the structures we have just seen in the previous section. On the right side of the ascending aorta is the superior vena cava look at it here this is the ascending aorta and on its right side is the superior vena cava and then behind the aorta is the trachea now the
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trachea has already bifurcated right main bronchus and left main bronchus and behind is the esophagus here on the left side is the descending aorta so ascending aorta, descending aorta and on the right side and behind the esophagus and on its right side is the azygos vein this vein that's going to terminate and drain into the superior vena cava higher up. Let's follow this vein the azygos
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vein in a higher section this is the azygos vein draining into the superior vena cava look at the superior vena cava and I will show it to you in a lower section so this is the superior vena cava, this is the ascending aorta and in a higher section again this is the ascending aorta; here is the descending aorta and again this is the descending aorta in a lower section. Now in this section, we can see the pulmonary trunk and it's giving rise to the left pulmonary artery,
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actually, the pulmonary trunk bifurcates into right and left pulmonary arteries but the left pulmonary artery goes a little bit higher than the right pulmonary artery that's why it can be seen in higher sections before we can see the right pulmonary artery. The left pulmonary artery can be seen higher up because it arches higher above the root of the left lung; so this is the root of the left lung here and here's the root of the right lung and
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the root of the right lung we can see the upper lobe bronchus that arises earlier from the right main bronchus no such bronchus is seen on the left side it's only the right upper lobe bronchus that arises earlier than the left. In the lung fields, I can see the oblique fissure here on the left side dividing the lump into two lobes the lower lobe which is located more or less posteriorly and the upper lobe which is located more or less anteriorly.
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This is a CT section almost at the same level as the previous section, we can see the sternum anteriorly, the vertebral body posteriorly and here again this is the ascending aorta and the descending aorta and this is the pulmonary trunk with the left pulmonary artery, the trachea, and esophagus; again, we will have a rapid look at the anatomical section so this is ascending, descending aorta and superior vena cava, the pulmonary trunk and the left pulmonary artery,
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ascending, descending aorta, superior vena cava, pulmonary trunk and left pulmonary artery. Now this section is a little bit lower down it is distal to the level of the bifurcation of the trachea so no more trachea will be seen here but we can see the descending aorta and the esophagus so here again in this section we can see anteriorly is the ascending aorta this is actually the beginning of the ascending aorta and on its left side, this is the pulmonary trunk
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giving rise to the left pulmonary artery and then the right pulmonary artery. In a section that is a little bit higher up than this one that is to say in the previous section we can only see the pulmonary trunk and the left pulmonary artery because the left pulmonary artery arches higher than the right pulmonary art so we need to go to a lower section in order to be able to see the right
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pulmonary artery. So this is the right pulmonary artery and again this is the superior vena cava here. The superior vena cava extends from the level of the right first costal cartilage to the level of the right third costal cartilage and here we can see the right and left main bronchi they are away from each other the structures that are located between them are the tracheobronchial
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lymph nodes inferior tracheobronchial lymph nodes we can also see another group of lymph nodes which are located at the hilum of the lung and these are the hilar lymph nodes or bronchopulmonary lymph nodes this is the esophagus and the descending aorta so here is the ascending aorta and this is the descending aorta. Just to remind you, the aorta begins as an ascending aorta here then it
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becomes an arch and then a descending aorta so in one transverse section we will be able to see the ascending aorta as a circle and the descending aorta as another circle. If the section passes through the arch of the aorta like what we have seen in an earlier section it will appear as an oval structure. The other vessels that we can see at the hilum of the lung for example this vessel is a pulmonary vein so we can see that at the hilum of the lung you can see a bronchus,
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pulmonary vein, and pulmonary artery these are the main structures that are located at the hilum in addition to the presence of lymph nodes and nerves and some other structures like bronchial arteries. Now this is a CT section almost at the level of the previous section here again we can see how the trachea is bifurcating here it's no more one circle it is like two circles here they are trying to get away from each other this is the superior vena cava and the ascending aorta
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and then this is the descending aorta and we can see the pulmonary trunk dividing into the left pulmonary artery and a right pulmonary artery. Behind the trachea is the esophagus. Now, this is a section a little bit lower down let's concentrate on the structures in the mediastinum so this is the ascending aorta here and the descending aorta and on the right side of the ascending aorta is the superior vena cava this is the right pulmonary artery and this
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is the right main bronchus of course after it has given the upper lobe bronchus. This is the left main bronchus here you can see that it is more oblique in section than the right main bronchus which is more or less vertical it is more in line with the trachea. This is the azygos vein. This is the superior vena cava, superior vena cava at almost at its entrance to the right atrium so we can see this piece of the right atrium here constituting the article,
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right article and you can see that the right article is clasping this region of the right ventricle; this is the infundibulum of the right ventricle it is the infundibulum that's going to give rise to the pulmonary trunk and here is the same side is the pulmonary trunk. The infundibulum is clasped on the right side it is clasped by the right auricle and on the left side it is clasped by the left auricle; so this is the left auricle, it is part of the left atrium.
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This is again a CT section almost at the level of the previous section where we can see the ascending aorta, descending aorta, on the side of the ascending aorta on the right side is the superior vena cava entering the right atrium and this is the right ventricle here constituting most of the anterior surface of the heart and is giving rise to the infundibulum that gives rise to the pulmonary trunk. Behind, is the region of the left atrium as we will see in the next section
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and here you can see how the bronchi are separated away from each other: the left main bronchus and the right main bronchus here and behind, this is the esophagus and this is the azygos vein. This is a section a little bit lower down this is the vertebral body this is the descending aorta and here's the azygos vein here is the esophagus and as you can see that just in the front of the esophagus is the posterior chamber of the heart which is the left atrium located posteriorly
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and you can see the close relationship of the esophagus and the left atrium that's why left atrial enlargement might indent the esophagus. What separates the esophagus and the left atrium is the oblique pericardial sinus, you can see how the left atrium is receiving the pulmonary veins, this is a pulmonary vein from the right side and pulmonary veins from the left side you can see their continuity with the roots of the lung and at the hilum of the lung if
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you look at the hilum again then you can see also the bronchi which are characterized by the presence of multiple rings of cartilage. On the right side of the heart, this is the right atrium here receiving the superior vena cava and this is the right ventricle, the infundibulum again of the right ventricle and this is part of the left ventricle the outflow tract of the left ventricle which is the vestibule that is going to give rise to the ascending aorta
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In this section which is a little bit lower down again look at the mediastinum you will find the descending aorta here on the left side, this is the azygos vein and the esophagus and in front of the esophagus again it is the left atrium which is the most posterior chamber of the heart receiving the pulmonary veins two veins on either side. On the right side here the right chamber is the right atrium and anteriorly you can see the
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right ventricle note that the right ventricle is thicker than the wall of the right atrium. This is another CT scan showing the heart, behind it is the esophagus, azygos vein and the descending aorta on the left side. In the heart, we can see some shadows of the left atrium, right atrium, vestibule of the left ventricle and right ventricle. In a lower section we can see the posterior structures in the mediastinum are the descending aorta, the azygos vein,
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esophagus, anterior to it is the left atrium receiving the pulmonary veins and this is the right atrium then the right ventricle and this is the left ventricle, very thick muscular wall if it is compared with the muscle wall of the right ventricle and this is also thick if it is compared with the muscle wall of the right atrium or the left atrium; we can see here evidence of the trabecula carneae and papillary muscles in the right ventricle. In the lung fields, the oblique
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fissures are clear whether on the right side or on the left side and on the left side we can see that the lung is excavated by a deeper cardiac impression than that on the right side and there is a tongue-like projection of the upper lobe of the left lung which is called the lingula. In a lower section, we will be able to see more of the features of the heart and the posterior structures of the mediastinum we can see the descending aorta, the azygos vein, and the
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esophagus. Just anterior to the esophagus we can see part of the left atrium and here is the right atrium on the right side the right atrioventricular orifice leading to the right ventricle; the right ventricle constitutes most of the anterior surface of the heart it has a thicker wall than the atria but it is thinner than the wall of the left ventricle. The left ventricle is forming the apex of the heart and this is the interventricular septum which
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is as thick as the wall of the left ventricle. Here the right atrioventricular orifice can be seen with the cusps of the tricuspid valve. Again, note that the cardiac impression on the left side is deeper than the cardiac impression on the right side and that the upper lobe of the left lung has a tongue-like projection which is called the lingula.
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This is a section lower down the previous one we can see that there is no more left atrium can be seen because the left atrium does not reach the diaphragmatic surface of the heart it's a little bit higher than the diaphragmatic surface of the heart. The diaphragmatic surface of the heart is formed by the right atrium, right ventricle and left ventricle. Instead of the left atrium, we can see the coronary sinus on its way to open into the right atrium; so this is the coronary
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sinus, it occupies the distance between the left atrium and the diaphragmatic surface of the heart so if we go a little bit higher here we can see some of the left atrium and the coronary sinus; a little bit higher, the left atrium can be clearly seen. But as we go closer diaphragmatic surface of the heart then no more left atrium can be seen. Posterior to the heart is the esophagus, behind it is the azygous vein and the descending thoracic aorta.
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Going a little bit down again we can see the right atrium and here something is going to open into the right atrium and that is the inferior vena cava. Here this is the right ventricle we can see a thicker wall than that of the right atrium; some trabecuale canii are seen and a papillary muscle can be seen also and this is the right atrioventricular orifice. This is the atrioventricular groove where we can see here vessels and this is the right coronary artery can
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be seen here. Again, this is the coronary sinus opening into the right atrium and you can see the thickness of the left ventricle, a very thick wall the interventricular septum is as thick as the thickness of the wall of the left ventricle and not the right ventricle and the left ventricle forming the apex of the heart. In this section, we can see that there is something new that appeared in the fields of the lung and this is the right dome of the diaphragm.
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The left dome of the diaphragm cannot be seen because the left dome is located a little bit lower than the right dome of the diaphragm. The right dome of the diaphragm is higher than the left dome because of the presence of the liver on the right side so you can see here in this model that the section as it passes through the right dome of the diaphragm cuts part of the liver; it does not pass through the left dome of the diaphragm because the left dome of the diaphragm
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is lower than the right dome of the diaphragm and the right dome of diaphragm is pushed up by the presence of the bulky liver mainly in the right hypochondria also we can see that the section can pass through the inferior vena cava as it passes through the central tendon of the diaphragm in order to open into the right atrium; so this is here again, right atrium, inferior vena cava and right dome of the diaphragm can be seen at the same level.
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Now in a section a little bit lower down this is the liver has been cut while on the left side, it's actually it is the left dome of the diaphragm. These are the lungs, posteriorly is the esophagus, descending aorta and the azygos vein. The heart shows the left ventricle with its thick wall, and right ventricle, this is a septomarginal trabecula or the moderator band which extends from the septum to the anterior wall of the right ventricle and
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here is the right atrioventricular orifice, right atrium receiving the inferior vena cava
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This is a CT section almost at the same level of the previous section and so you can see here the liver on this side but on the other side on the left side it's still the heart can be seen. This is the liver and here is the site of the inferior vena cava,
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here is the site of the liver, this is the liver here and here's the esophagus and the aorta. A lower section like this level will pass through the liver, pass through the stomach and the spleen on the left side but it can still pass through the lower lobe of both lungs so here this is the lowermost section that I'm going to describe today so here there's the liver on the right side on the left side is the stomach you can see the rugae
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of the stomach and the esophagus opening into the stomach. Behind the stomach is the spleen and behind the spleen is the diaphragm. Behind the diaphragm, you can see evidence of the lower lobe of the left lung and here again you can see the lower lobe of the right lung it looks as if it is behind the liver but actually it is the thin diaphragm that is separating the two the liver is located in the abdominal cavity below the diaphragm and the lung is located in
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the thoracic cavity above the diaphragm here behind the esophagus we can see the aorta. So this CT section is almost at the same level as the previous anatomical section you can see the liver you can see the stomach esophagus and this is the spleen here and the aorta and these are the lung fields that can still be seen: right lung field and left lung field
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