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This arch divides into a maxillary process and a mandibular process, giving rise to structures including the bones of the lower two-thirds of the face and the jaw. The maxillary process becomes the maxilla (or upper jaw, although there are large differences among animals [11]), and palate while the mandibular process becomes the mandible or lower jaw.
The pharynx arises during development in all vertebrates through a series of six or more outpocketings on the lateral sides of the head. These outpocketings are pharyngeal arches, and they give rise to a number of different structures in the skeletal, muscular, and circulatory systems. The structure of the pharynx varies across the vertebrates.
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.
The palatopharyngeal arch (pharyngopalatine arch, posterior pillar of fauces) is larger and projects further toward the middle line than the palatoglossal arch; it runs downward, lateralward, and backward to the side of the pharynx, and is formed by the projection of the palatopharyngeal muscle, covered by mucous membrane.
Continuous with the dorsal end of the first pharyngeal arch, and growing forward from its cephalic border, is a triangular process, the maxillary prominence (or maxillary process), the ventral extremity of which is separated from the mandibular arch by a ">"-shaped notch.
This arch originates maxillar and mandibular prominences, part of the temporal bone and Meckel's cartilage (malleus and incus) as skeletal structures. The second pharyngeal arch is innervated by the facial cranial nerve. Muscles that arise from the arch are those involved with facial expression and the posterior digastric muscle.
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 ...