As medical students, we could not have dared to appear for the final year undergraduate examination without knowing why the thyroid gland moves up with deglutition and the central role played by the “ligaments of Berry” in this context.
The thyroid gland is enclosed by the pre-tracheal fascia which condenses to form the ligaments of Berry (lateral thyroid ligaments) which act as “suspensory ligaments”, attaching the thyroid gland to the larynx and trachea. Ligaments of Berry were first described by James Berry (1860 – 1946). Sir James Berry was born at Kingston, Ontario, Canada, but was educated in London and worked in England till his death (1946). He served as the President of the Royal Society of Medicine (1926-8).
He described that each lateral lobe of the thyroid gland is attached by a firm band of fibrous tissue, the lateral ligament, to the side of the cricoid cartilage and the first two or three rings of the trachea. These came to be known as the “suspensory ligaments” of Berry.
There is no doubt in anybody’s mind (including mine), that they play a part in suspending the thyroid lobes and thus contribute to the upward movement of the gland during deglutition.
In the course of the thyroidectomies that I have performed, assisted, or seen being performed, there has been one finding which I have constantly observed - that the thyroid gland (especially the isthmus) has to be literally “dissected” away from the trachea. I do not recollect seeing a case wherein the thyroid gland could be just “lifted off” (or, peeled off) the trachea. One may, rightly so, explain that most of these glands were perhaps badly diseased and therefore, adherent to the trachea. Well, that may be the case, but as I have not had the opportunity to perform a thyroidectomy for a non-thyroidal cause so far, I can’t confirm.
Two examples in which a thyroidectomy is indicated in non-thyroidal diseases include,
- as part of wide resections for laryngeal cancers, and
- for parathyroid cancers.
In these situations, the thyroid per-se is normal (undiseased). If the thyroid isthmus can be easily lifted off the trachea in these situations, my contention will be proven wrong.
Tracheostomy is another situation worth mentioning. It may be noticed in the course of “open” tracheostomies, when the isthmus needs to be divided, how easy or difficult it is, to raise the isthmus from the trachea and retract the cut ends to either side after division.
In one article on emergency tracheostomy, published by the German Society for Tropical Surgery, the author makes this following explicit statement - “Put a small haemostat into the incision and feel behind his thyroid isthmus and its fibrous attachment to the front of his trachea. When you have found the plane of cleavage, use blunt dissection to separate the isthmus from the trachea”. Mind you, a good number of these isthmuses (during emergency tracheostomies) are likely to belong to otherwise ‘normal’ thyroid glands.
Text books of anatomy do not mention anything specifically about the space between the isthmus and the trachea. This information is not available from imaging (CT and MRI) findings. One may not be wrong to assume that the isthmus can easily be lifted off the surface of the trachea, if there was an areolar tissue plane at this location. There is no specific mention about such a plane in the anatomical or radiological sources (to the best of my knowledge). The presence of a ‘bloodless’ areolar space between the upper pole of the thyroid and the cricothyroid muscles is well described. This space is very useful in dissecting the upper pole and in avoiding injury to the external laryngeal branches of the superior laryngeal nerves.
Therefore, my humble contention is that if the isthmus of the thyroid gland has some normal fixity to the trachea and my experience is that it does, then, this in itself must be sufficient to cause the thyroid to move up on deglutition, regardless of the contribution of the ligaments of Berry. I am not in any way trying to minimize the role played by the suspensory ligaments of Berry, but would like to know from the experiences of others especially, those with experience in thyroidectomies for non-thyroidal conditions; radiologists with experience in imaging features in normal thyroids with respect of the space behind the isthmus; and anatomists as well as other colleagues.
Finally, I humbly call for some introspection. While exposing the thyroid (especially so, for emergency tracheostomies), after the pre-tracheal fascia has been incised and isthmus exposed, if one picks up the isthmus and lifts it, will it simply come off the trachea? Will it be possible to lift it up and move it freely up and down? If your answer is “yes”, then, maybe the thyroid isthmus is not fixed to the trachea after all.
The question is “are the ligaments of Berry the only reason why the thyroid moves up with deglutition?”
Would the medical students of the future, continue to “worry” about not knowing only “Berry”?
CITE THIS ARTICLE:
M. Aroon Kamath, M.D.. Are the ligaments of Berry the only reason why the thyroid moves up with deglutition?. Doctors Lounge Website. Available at: http://www.doctorslounge.com/index.php/blogs/page/13485. Accessed May 24 2013.
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