04/09/2023 at 10:29 am #53278Jayeta ChoudhuryParticipant
I have heard in an YouTube lecture that the omohyoid muscle crossing in the neck can be used as a landmark for differentiating level III and IV node levels. Do you believe that? I think I do.
04/09/2023 at 11:28 am #53281Stephen BirdKeymaster
Yes, the omohyoid muscle really is one of my favourite muscles.
Would you believe it connects your hyoid bone in your neck to the scapula !
Certainly a cool muscle.
The function of this muscle is to depress the hyoid bone and larynx and reestablish breathing following the act of swallowing. In addition, the omohyoid muscle maintains a low pressure in the internal jugular vein by tensing the carotid sheath. So it is very important.
The boundary between level 3 and level 4 in the AJCC cervical lymph node levels can be tricky.
The inferior boundary of level 3 and the upper border of level 4 is the cricoid cartilage.
The way I find the cricoid cartilage is to come up the thyroid in the midline and when I found the isthmus crossing over the trachea I am getting close. Keep scanning slowly superiorly and you as you come out of the isthmus you will see a layer of cartilage appear over the trachea. It appears hypo echoic and looks a bit like a saddle draping over the trachea. Once you identify the cricoid cartilage you can draw a line out laterally and this represents the boundary between level 3 and 4.
When you draw this line out under the sternocleidomastoid (SCM) muscle you will see the OMOHYOID muscle under the SCM. So you can use the omohyoid under the SCM as another marker of the boundary between level 3 and 4.
Another cheats way of doing it is to use the thyroid gland. If you think about how I found the cricoid cartilage it makes sense that if you are seeing the thyroid gland in the image you are more likely in level 4 as level 3 is above the isthmus. This is not perfect as you may have a bit of the upper poles of the thyroid on level 3 images, especially if the thyroid is enlarged. So it is not perfect, but if you show me images and I can see plenty of thyroid and in particular the isthmus I am happy to say you are in level 4.
Have a great week scanning up there is beautiful Durgapur in West Bengal, India.
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04/09/2023 at 10:53 pm #53312Jayeta ChoudhuryParticipant
Thanks again. Even I don’t believe that I am learning so much from someone so far away.
06/09/2023 at 10:08 am #53359Stephen BirdKeymaster
You are very welcome,
The great thing about the website is that geography doesn’t matter,
No matter where you are it is accessible.
I would love your colleagues to also enjoy the website.
Spread the word!
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