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The pharyngeal arches, ... with 1 being the arch closest to the head of the embryo, and arch 5 existing only transiently. ... By differential growth the neck ...
The first and second arches disappear early. A remnant of the 1st arch forms part of the maxillary artery, [3] a branch of the external carotid artery. The ventral end of the second develops into the ascending pharyngeal artery, and its dorsal end gives origin to the stapedial artery, [3] a vessel which typically atrophies in humans [4] [5] but persists in some mammals.
Plus, each arch has its own arterial component. When neural cells migrate to the arches and surround them, they begin to increase in size. [4] The six pharyngeal arches give rise to much of the skeletal and muscular tissue in the head and neck region. When the embryo is 42 days old, the mesenchymal arches can be recognized with its ...
Pharyngeal arches appear in all tetrapod embryos: in mammals, the first pharyngeal arch develops into the lower jaw (Meckel's cartilage), the malleus and the stapes. Haeckel produced several embryo drawings that often overemphasized similarities between embryos of related species. Modern biology rejects the literal and universal form of Haeckel ...
At the beginning of the ninth week, the embryo is termed a fetus (spelled "foetus" in British English). In comparison to the embryo, the fetus has more recognizable external features and a more complete set of developing organs. Human embryology is the study of this development during the first eight weeks after fertilization.
The cervical sinus is bounded in front by the second pharyngeal arch (hyoid arch), and behind by the thoracic wall. The second pharyngeal arch (hyoid arch) grows faster than the other pharyngeal arches, so they become covered. It is ultimately obliterated by the fusion of its walls by the 7th week of gestation.
Originally it was the lower of two cartilages which supported the first branchial arch in early fish. Then it grew longer and stronger, and acquired muscles capable of closing the developing jaw. [1] In early fish and in chondrichthyans (cartilaginous fish such as sharks), Meckel's cartilage continued to be the main component of the lower jaw.
Pattern of the pharyngeal arches. I-IV pharyngeal arches, 1–4 pharyngeal pouches (inside) and/or pharyngeal grooves (outside) a Tuberculum laterale b Tuberculum impar c Foramen cecum d Ductus thyreoglossus e Sinus cervicalis. The pharyngeal apparatus is an embryological structure. [1] [2] It consists of: pharyngeal grooves (from ectoderm ...