Embryological origin of laryngeal cartilages - USMLE Forums
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Old 01-12-2011
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Zygote Embryological origin of laryngeal cartilages

do they arise from mesoderm , or neural crest ?
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Old 01-12-2011
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They arise from fusion of the fourth and sixth branchial arches, so they are derived from mesoderm
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Old 01-12-2011
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Originally Posted by 3TTah View Post
They arise from fusion of the fourth and sixth branchial arches, so they are derived from mesoderm
What 3TTah said - although I thought that the thyroid and epiglottic were from the fourth arch and the cricoid, arytenoids, corniculates and cuneiforms came from the sixth arch?
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Old 01-13-2011
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i have found that cartillage develops from mesoderm and such is written in high yield histology . but kaplan notes of anatomy for head and neck , in the table heading for skeletal structures derived in pharyngeal arches has neural crest written in bracket under the heading . plz help
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Old 01-14-2011
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Originally Posted by laxitjn View Post
i have found that cartillage develops from mesoderm and such is written in high yield histology . but kaplan notes of anatomy for head and neck , in the table heading for skeletal structures derived in pharyngeal arches has neural crest written in bracket under the heading . plz help
Fast answer:
Neural crest cells form the cartilages of the face, the incus and malleus in the ear, and the hyoid bone - which is probably what the Kaplan notes are referring to...

(longer answer continues below)
...but they also form or induce connective tissue and glands in and around all the arches. When I think of neural crest cells in the neck area, I think of the hyoid; induction of the thymus, thyroid, and parathyroid glands; their contribution to the muscular arteries arising from the aortic arches; and of course the dorsal root and autonomic ganglia (remember the achalasia that results from destruction of the parasympathetic ganglia in Chagas disease?).

The complicated story of neural crest cells is still unfolding, of course, and has been mostly inferred from tracking marked cells in developing embryos and looking at what happens in animal embryos when neural crest cells are ablated. It is also still problematic to determine whether neural crest cells induce the formation of some structures externally (like an architect telling construction workers what to make), internally (like a piece of sand seeding a pearl), or absolutely (like a nut growing into a tree). For our purposes, it doesn't matter yet until it informs pathophysiology...

Here is a good chart about pharygeal arch derivatives from Gilbert's Developmental Biology, which is available to the public through NCBI: http://www.ncbi.nlm.nih.gov/books/NBK10065/

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thanks for that extensive and detailed reply
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