[Music] hello everyone this is the second video in this series on interpreting chest x-rays the topic is the systematic approach and normal chest x-ray Anatomy the learning objectives of this video are to be familiar with the systematic approach to interpreting chest x-rays and to know the correlation between anatomy and normal Shadows on the X-ray before just presenting a systematic approach I first wanted to mention a couple of important principles about it a systematic approach is most important for the clinician's least experience with reading chess xrays since it reduces the chance that important findings will be missed all aspects of Chess x-ray interpretation should be included the individual elements of the approach should be examined in a sequence that's either logical and or easy to remember and there is no one best system though all should begin with an assessment of the film's technical quality so the system I teach trainees is informally referred to as the ABCDEF system it's not the only one but it's certainly the most common at least in the US it's also not perfect but it's easy to remember each of those six letters refers to a specific anatomic structure even before the a we need to assess the technical quality then a stands for Airways B for bones and soft tissue C for the cardiac silhouette and medyum D for diaphragm which also includes assessment of the gastric air bubble usually located under the left Hemi diaphragm e for fusions in other words assessment of the plur which actually includes findings Beyond just plural fusions and F for fields that is the lung Fields lastly although it's not explicitly part of the neonic is an assessment of lines tubes devices and prior surgeries such as sternotomies and valve Replacements aside from the fact that it's easy to remember another nice thing about this pneumonic is that the lungs are examined near the end this is a good idea because normally the lungs are the area of greatest interest and the most likely to be abnormal therefore once the clinician finds an abnormality there it's very easy for him or her to forget examining the rest of the film I've seen more than one rib fracture missed due to distraction over acute lung pathology you may have noticed that the list of items here lines up really nicely with the remaining videos in this series which of course is not a coincidence but before you can identify pathology of each of these anatomic structures you first need to know where where they are on the X-ray and what they normally look like so let's go through the X-ray anatomy of a to f one at a time as is for the Airways there are three anatomic Airway structures that are typically visible on a normal x-ray they are the trachea which is normally in the midline and the right and left main bronchus remember that the patient's right will be on the left side of the screen to help you visualize these structures let me superimpose a drawing of them the left main bronchus tends to take off from the trachea at a slightly more horizontal angle as compared to the right which is why aspirated foreign bodies if small enough are more likely to end up in the right lung than the left and it's also why endot tral tubes if Advance too far end up in the right main broncus blocking off ventilation to the left rather than vice versa I'll take the drawing away again so you can try to see the Airways on your own the next set of structures is the bones there are four types of Bones easily visualized on a PA and lateral x-ray set first is this structure which as you probably know or could guess is a rib there are two radiographic components of the rib on the PA film the posterior rib which is easier to see and is oriented horizontally and the anterior rib which is harder to see and oriented at a 45° angle the next bone is the clavicle located up here there's obviously a right and a left one the sternum is sometimes visible on the lateral film but is often obscured by soft tissue in the anterior chest wall then are the vertebral bodies more easily visible on the lateral film but usually seen on the PA as well provided that the technical quality is adequate then there is the cardiac silhouette and the medus dyum which I think logically should be evaluated together there are a lot of anatomic structures which compose the silhouette here I'll start by outlining it and then label what each bump knob or side corresponds to you will usually also be able to see another vertical line running just to the patient's left of the vertebral bodies which corresponds to the left side of the descending aorta to make it easier to visualize here's a drawing of the heart and great vessels the one structure on the patient's left called the aoro pulmonary window may be unfamiliar to some viewers this is an important space between the aortic Arch and the pulmonary artery where one will find the recurrent lenial nerve and lymph nodes and then I'll take the drawing away and try to appreciate those various structures moving on the diaphragm and plora which also make sense to evaluate together so here are the right and left Hemi diaphragms as seen on the PA view it is normal for the right Hemi diaphragm to be slightly higher than the left presumably due to the liver directly beneath it while looking at the diaphragms it's important to remember that there aren't any truly flat structures in the body for example the Hemi diaphragms are curved in three-dimensional space as you might be able to appre iate from comparing the PA to the lateral the heavy diaphragms that's seen on the PA really just represent the superiormost aspect of the diaphragms the plora which is a double membrane that surrounds each lung is outlined here but is normally invisible due to its thinness however knowledge that the plora is there is essential for diagnosing a pneumothorax plural plaques from asist exposure and plural thickening in addition there are spaces on either side where the diaphragm meets the thoracic wall these two spaces seen on the PA are usually called the right and left costophrenic angles though the term costophrenic sulai would probably be more semantically accurate in most circumstances the space in the back on the lateral film has several very similar names the most common of which is the posterior costophrenic angle there's also usually a small pocket of air visible under the left h diaphragm this usually represents air in the stomach in which case it's called the gastric air bubble although occasionally it can be unclear as to whether the gas is in the stomach or in the intestines finally the last structures on the chest x-ray are of course the lungs the anatomic structures in the lungs to worry about when interpreting x-rays are the fissures between the loes and the loes themselves first is the horizontal fissure located here there's only one and it's on the right side here is its location on the lateral film it's the only one of the three fissures that is commonly visible in normal x-rays which is because a significant portion of the plane of the fissure is parallel to the direction of the X-ray beams however it's only visible on the PA which is why the fissure there is represented by a solid line and the fissure on the lateral is represented by a dotted line then there are the right and left oblique fissures neither of which is usually visible in either view as you can probably guess if you didn't already know it the fact that there are two fissures on the patient's right meaning that the right long is divided into three loes while the one fissure on the left divides the left long into two loes here's the location of the right upper lobe and the right middle lobe and finally the right lower lobe notice that because the oblique visure runs obliquely as seen in the lateral view the lower lobe extends almost all the way to the apex of the lung this will be true on the left side as well as a consequence if only the PA or AP views are presented without a lateral it's almost impossible to tell what lobe a visualized nodule or mass is located in unless it's seen in the uppermost part above the lower lob's most Superior extent here's the left upper lobe and finally the left lower lobe that concludes this video on the systematic approach and normal chest x-ray Anatomy if you found it helpful please remember to like or share it the next video will discuss the assessment of a chest film's technical quality