Branchial Groove
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A pharyngeal groove (or branchial groove, or pharyngeal cleft) is made up of ectoderm unlike its counterpart the pharyngeal pouch on the
endoderm Endoderm is the innermost of the three primary germ layers in the very early embryo. The other two layers are the ectoderm (outside layer) and mesoderm (middle layer). Cells migrating inward along the archenteron form the inner layer of the gastr ...
al side. The first pharyngeal groove produces the
external auditory meatus The ear canal (external acoustic meatus, external auditory meatus, EAM) is a pathway running from the outer ear to the middle ear. The adult human ear canal extends from the auricle to the eardrum and is about in length and in diameter. Str ...
(ear canal). The rest (2, 3, and 4) are overlapped by the growing
second pharyngeal arch The pharyngeal arches, also known as visceral arches'','' are transient structures seen in the embryonic development of humans and other vertebrates, that are recognisable precursors for many structures. In fish, the arches support the gills an ...
, and form the floor of the depression termed the
cervical sinus The cervical sinus is a structure formed during embryonic development. It is a deep depression found on each side of the neck. It is formed as the second pharyngeal arch (hyoid arch) grows faster than the other pharyngeal arches, so they become ...
, which opens ventrally, and is finally obliterated.


See also

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Branchial cleft cyst A branchial cleft cyst or simply branchial cyst is a cyst as a swelling in the upper part of neck anterior to sternocleidomastoid. It can, but does not necessarily, have an opening to the skin surface, called a fistula. The cause is usually a devel ...
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Collaural fistula Collaural fistula or cervico-aural fistula is a type of fistula whose openings are at external auditory canal and the neck, usually in the upper part of anterior border of sternocleidomastoid muscle. It occurs at birth because the defect is in th ...


References

Animal developmental biology Pharyngeal arches {{developmental-biology-stub