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.
Under surface of the head of a human embryo about twenty-nine days old.
|Latin||arcus pharyngeus primus|
The first branchial arch, also called the first pharyngeal arch and mandibular arch, is the first of six pharyngeal arches that develops in fetal life during the fourth week of development. It is located between the stomodeum and the first pharyngeal groove.
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), and palate while the mandibular process becomes the lower jaw. This arch also gives rise to the muscles of mastication.
Meckel's cartilage forms in the mesoderm of the mandibular process and eventually regresses to form the incus and malleus of the middle ear, the anterior ligament of the malleus and the sphenomandibular ligament. The mandible or lower jaw forms by perichondral ossification using Meckel's cartilage as a 'template', but the mandible does not arise from direct ossification of Meckel's cartilage.
The skeletal elements and muscles are derived from mesoderm of the pharyngeal arches.
Derivatives of the first arch:
- Malleus & Incus of the middle ear
- maxilla & mandible
- spine of sphenoid bone
- Sphenomandibular ligament
- palatine bone
- squamous part of temporal bone
- Anterior ligament of malleus
- Muscles of mastication (chewing)
- Mylohyoid muscle
- Digastric muscle, anterior belly
- Tensor palati muscle
- Tensor tympani muscle
The mandibular and maxillary branches of the trigeminal nerve (CN V) innervate the structures derived from the corresponding processes of the first arch. In some lower animals, each arch is supplied by two cranial nerves.The nerve of the arch itself runs along the cranial side of the arch and is called post-trematic nerve of the arch.Each arch also receives a branch from the nerve of the succeeding arch called the pre-trematic nerve which runs along the caudal border of the arch.In human embryo,a double innervation is seen only in the first pharyngeal arch.The mandibular nerve is the post-trematic nerve of the first arch and chorda tympani (branch of facial nerve) is the pre-trematic nerve.This double innervation is reflected in the nerve supply of anterior two-thirds of tongue which is derived from the first arch.
- William J. Larsen (2001). Human embryology. Edinburgh: Churchill Livingstone. ISBN 0-443-06583-7
- Harris, Edward F., 2002.Craniofacial Growth and Development.
- Inderbir Sing,G.P Pal-Human Embryology
- McMinn, R., 1994. Last's anatomy: Regional and applied (9th ed).
- hednk-011 — Embryo Images at University of North Carolina
- Overview at University of Newcastle
- Overview at Howard University
- Mnemonic:First branchial arch