File:Frazer1914 fig03.jpg

Fig. 3. Left recess from a model 27 mm Embryo

Observe that the forward extension, A, from third arch along the floor is much more marked and prominent than in the last figure, and has reached the first arch.

The further development of the region up to the third month is a simple progression of the changes seen in their early stages in fig. 2. The first arch area stands up more, the manubrial district of the second arch is more prominent and defined, and the second pouch is recognisable between the styloid bar and the glosso-pharyngeal nerve. But a distinct change is visible when attention is directed to the third arch region; the arch, presumably as" a result of its growth, is encroaching on the lumen of the inner portion of the cavity from behind, so that already some indication of a division into tubal and tympanic parts is foreshadowed. A drawing of one of the models showing this stage is seen in fig. 3, and it is interesting to compare it with the earlier condition: recognition of the first and second arch region is easy, and the districts into which the latter is subdivided are evident and unmistakable.

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Links: Fig 1 | Fig 2 | Fig 3 | Fig 4 | Fig 5 | Fig 6 | 1914 Frazer | Pharyngeal arches | Historic Embryology Papers

Reference

Frazer JE. The second visceral arch and groove in the tubo-tympanic region. (1914) J Anat Physiol. 48(4): 391-408. PMID 17233005

Cite this page: Hill, M.A. (2024, April 27) Embryology Frazer1914 fig03.jpg. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/File:Frazer1914_fig03.jpg

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