Identifying structures of the neck using ultrasound
Learn how to differentiate between various structures of the neck with the help of ultrasound.
If you need to place a central line and you're just a tad bit terrified that you'll insert it into the wrong place, this is the video for you. By the end of this video from our Procedural Ultrasound Masterclass, you'll know how to identify the important structures of the neck, including the sternocleidomastoid muscle, external jugular vein, carotid artery, and internal jugular vein using ultrasound.
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[00:00:00] The approach for an internal jugular vein, central line placement, is typically the lateral neck. Unless there's a contraindication, the right internal jugular is preferred to the left, due to a more direct path to the superior vena cava. Let's take a look at the vessels of the neck. In this anatomical cartoon, you can see the structures of the lateral neck with the internal jugular, carotid, nerve roots, lymph nodes, thyroid, external jugular, and trachea in view. I'll give you a second to look at this.
[00:00:30] This is a cross-sectional image of the mid-anterior neck. Here, you can see the relationship of the internal jugular vein to the carotid artery and the other structures of the neck. This will be very important to orient yourself to the cross-sectional images you'll see on ultrasound. There are two approaches for looking at the internal jugular vein. In the transverse access, this will be a cross-sectional view of the
[00:01:00] vessels and they'll look more rounded. I have found that placing the probe, so that the picture on the screen makes anatomical sense, has been the most helpful. So, in this case, the indicator would go towards the midline if you were doing a right internal jugular vein cannulation. So, the carotid is medial and the IJ is lateral.
[00:01:30] The rest of the lesson, we'll use this orientation. So, if attempting to place a left internal jugular line, the probe would point towards the patient's left, so that the carotid is medial and the IJ is lateral. Here, is general probe placement for longitudinal or sagittal access. The vessels here will appear as tubes. The probe should be perpendicular to the skin, and the indicator towards the head. Let's take another look at the vessels in transverse or short access. Here, is a view of the carotid artery and a view of the internal jugular vein in transverse view. You can see the internal jugular vein is just lateral and a little bit superior to the carotid artery. Since we're in the transverse view,
[00:02:00] the vessels look more rounded or circle or oval, since the view is taking a cross-sectional cut of the vessels. As you can see, the artery has thicker walls and is pulsatile, whereas the vein appears relatively more oval, thin-walled, and is compressible. Here, you can see the relationship between the internal jugular vein and carotid artery on the left side of the neck. Here is the vein, more oval and thin-walled
[00:02:30] compared to the artery, which appears medial, more round with a thicker wall. Here, is that same view approaching on the left. This time, the operator has used Doppler over the vessels. Here again, you see the internal jugular vein and the carotid artery. You can see that the vessels are lighting up on Doppler. The artery appears red, which means that relative to the probe, there is blood flowing towards it
[00:03:00] in this vessel, compared to the vein here, appears blue. That is because the blood is flowing away from the transducer in this case. Something that might surprise you is that the carotid is not always medial to the internal jugular vein. So, if you remember the orientation from this picture, this diagram shows that there are several anatomic variants of how the internal jugular vein is positioned, compared to the carotid in the neck. One study even found that 1 in 200 patients had an internal
[00:03:30] jugular vein that was actually medial to the carotid. Here, you can see an example of the larger internal jugular vein on top of the smaller round carotid. Okay, now let's take a look at the internal jugular vein and carotid in longitudinal or sagittal access, when the vessels will appear like tubes. Here, is a view of the carotid artery. You can see it looks like a long tube, you can see the pulsations and the thick wall.
[00:04:00] Here, is the internal jugular vein. You can see the wall is fairly thin and it's picking up some of the pulsations from the carotid in the bottom part of the screen but for the most part, you can see it's not pulsating on the top here. Here, is a clip fanning lateral to medial, in long access. So, you see the, IJ first here, then the carotid, and then the solid looking structure, which is
[00:04:30] actually the thyroid. IJ, carotid, thyroid. So, as you can see, again, the operator is fanning from lateral to more medial structures. Now, we can talk about other structures you may encounter in the lateral neck, one of these is muscles. Here, you can see the muscles of the anterior neck. The striated structure you see here is the
[00:05:00] sternocleidomastoid muscle. The operator, here, is bringing the probe from the clavicle up to the mandible. You can also see the anterior scalene in this view. Here, is the SCM muscle and here, is the anterior scalene. Because of the close proximity of the brachial plexus, it's important to be mindful of the nerve roots in the area. Here, are the important nerves in the anterior neck, the right
[00:05:30] brachial plexus. Here, you can see the C5 and C6 nerve roots bordered by the anterior and middle scalene muscles. Here, you can see these nerve roots are round and could fool you into thinking that they are vessels. Sometimes it's really hard to tell the difference between vessels and other structures. Here, you see the circular nerve roots more clearly, with their hypoechoic centers, with no flow to them on Doppler.
[00:06:00] This cross-sectional image of the anterior neck, you can see the relationship of the thyroid and trachea to the internal jugular vein and the common carotid. The solid structure you see here is the thyroid. The trachea is just behind, with cartilage rings and air within it, that causes shadowing downward. There are also several chains
[00:06:30] of lymph nodes, in the neck, that you may encounter. Lymph nodes are rounded heterogeneous structures that are blind- ending. Here, you can see one behind the left IJ. Here is another example of a lymph node, rounded and blind-ending. Putting it all
[00:07:00] together, you should now be familiar with all the structures in this image. Where is the carotid? Where is the internal jugular? There are a few tricky things about this slide. Here, the operator couldn't initially find the internal jugular because they are putting too much pressure on the vessel and collapsing it. Here, you can still see that the IJ is still very narrow. That sometimes happens when people are really dehydrated. Their IJ can appear very small. That's something to be mindful of when you're out searching for it.
[00:07:30] Nice work. You're now an expert on the sonographic anatomy of the anterior neck.