Pharyngeal arch

Pharyngeal arch

Infobox Embryology
Name = Branchial arch
Latin =
GraySubject = 13
GrayPage = 65


Caption = Schematic of developing fetus with first, second and third arches labeled.


Caption2 = Floor of pharynx of human embryo about twenty-six days old.
System =
CarnegieStage = 10
Precursor =
GivesRiseTo =
MeshName = Branchial+Arches
MeshNumber = A16.254.160
DorlandsPre = a_57
DorlandsSuf = 12149648
In the development of vertebrate animals, the pharyngeal arches (also called branchial arches or gill arches in fish) develop during the fourth and fifth week "in utero" as a series of mesodermal outpouchings on the left and right sides of the developing pharynx. In fish, the branchial arches give rise to gills.

Development

These grow and join in the ventral midline. The first arch, as the first to form, separates the mouth pit or stomodeum from the pericardium. By differential growth the neck elongates and new arches form, so the pharynx has six arches ultimately.

Each pharyngeal arch has a cartilaginous bar, a muscle component which differentiates from the cartilagenous tissue, an artery, and a cranial nerve.Each of these is surrounded by Mesenchyme. Arches do not develop simultaneously, but instead possess a "staggered" development.

Relations

Pharyngeal or branchial pouches form on the endodermal side between the arches, and pharyngeal grooves (or clefts) form from the lateral ectodermal surface of the neck region to separate the arches. [cite web |url=http://www.med.howard.edu/anatomy/gas/wk7/Lecture%2024.htm |title=Lecture 24. Branchial Apparatus |accessdate=2007-09-09 |format= |work=]

The pouches line up with the clefts, and these thin segments become gills in fish.

In mammals the endoderm and ectoderm not only remain intact, but continue to be separated by a mesoderm layer.

pecific arches

There are six pharyngeal arches, but in humans the fifth arch only exists transiently during embryologic growth and development. Since no human structures result from the fifth arch, the arches in humans are I, II, III, IV, and VI. [cite web |url=http://isc.temple.edu/marino/embryology/parch98/parch_text.htm |title=Text for Pharyngeal Arch Development |accessdate=2007-09-09 |format= |work=]

More is known about the fate of the first arch than the remaining four. The first three contribute to structures above the larynx, while the last two contribute to the larynx and trachea.

Use in staging

The development of the pharyngeal arches provide a useful morphological landmark with which to establish the precise stage of embryonic development. Their formation and development corresponds to Carnegie stages 10 to 16 in mammals, and Hamburger-Hamilton stages 14 to 28 in the chicken.

ee also

* Aortic arches
* Branchial pouch
* Branchial cleft cyst

References

External links

*


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Look at other dictionaries:

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  • pharyngeal arch — a segment of the lateral wall of the pharynx that will form jaw and gill structures. The anterior two arches form jaw structures and the following 5 arches form gill structures. Each arch is separated from its neighbours by an endodermal… …   Dictionary of ichthyology

  • pharyngeal arch — noun : branchial arch …   Useful english dictionary

  • First pharyngeal arch — First branchial arch Diagram showing the regions of the adult face and neck related to the fronto nasal process and the branchial arches …   Wikipedia

  • second pharyngeal arch — in the human embryo, the pharyngeal arch just caudal to the first pharyngeal arch; it later differentiates into the stapes, styloid process of temporal bone, stylohyoid ligament, lesser horn of the hyoid bone, and cranial part of the hyoid bone.… …   Medical dictionary

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  • pharyngeal cartilage — pharyngeal arch cartilage one of the rods of cartilage in the mesenchyme of the pharyngeal arches of the embryo, from which the cartilaginous viscerocranium develops …   Medical dictionary

  • first pharyngeal arch — the first of the pharyngeal arches in the human embryo, later differentiating into the sphenomandibular and anterior malleolar ligaments, malleus, and incus; it also gives rise to two prominences (the maxillary and mandibular prominences), from… …   Medical dictionary

  • pharyngeal arches — term used to denote the branchial arches (q.v.) in human embryos. The first and second pharyngeal arches (qq.v.) contribute to the formation of the upper and lower jaws and the hyoid bone. The third pharyngeal arch develops into the greater horn… …   Medical dictionary

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