Corpus: Branchial arch

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Synonyms: pharyngeal arch, visceral arch, branchial arch, pharyngeal arch, arcus branchialis
English: , visceral arch

Definition[Bearbeiten]

The gill arches are gill-like folds of the cephalic gut during the early embryonic period of humans.

Classification[Bearbeiten]

  • 1st gill arch (mandibular arch)
  • 2nd gill arch (hyoid arch)
  • 3rd gill arch (pharyngobranchial arch)
  • 4th gill arch
  • 5th gill arch
  • 6. gill arch

Development[Bearbeiten]

The gill arches are formed by growths of the mesenchyme between the 3rd and 5th week of embryonic development. Seen from the outside, they are separated from each other by 4 gill furrows (sulci branchiales), from the inside by 4-5 gill slits or pharyngeal pockets (sacci pharyngeales). Cells of the segmentally organised rhombomeres of the neural crest migrate into them.

In humans, a distinction is made between 6 gill arches, whereby the 5th gill arch is only rudimentary. The 1st and 2nd gill arches develop first, followed by the 3rd and 4th gill arches. In the course of the 6th week, the 2nd gill arch overgrows the 3rd and 4th gill arches, which passively form the base of the cervical sinus.

Derivatives[Bearbeiten]

Each gill arch subsequently develops a cartilage element, a muscle anlage, an associated gill arch nerve and an associated gill arch artery and vein. Some of these branchiogenic derivatives are preserved and can be assigned to a gill arch. However, there are contradictory statements in the literature. The following table provides an overview of the derivatives of the various gill arches (KB).

KB Nerve Muscles Skeletal elements Arteries
1
  • Mandibular nerve (V3) of the trigeminal nerve
  • If applicable, maxillary nerve (V2) of the trigeminal nerve
  • Chewing muscles
  • mylohyoid muscle
  • Musculus digastricus (venter anterior)
  • Musculus tensor veli palatini
  • Tensor tympani muscle
  • Meckel's cartilage (template for mandible)
  • Maxilla
  • Incus
  • Malleus
  • Os palatinum
  • Ala major ossis sphenoidalis
  • Os zygomaticum, if applicable
  • Temporal bone (pars squamosa)
  • Sphenomandibular ligament
  • Dentin and cementum of the teeth
  • maxillary artery, if applicable
  • External carotid artery, if applicable
  • Arteria canalis pterygoidei
2
  • Facial nerve with chorda tympani
  • Mimic musculature incl. platysma
  • Buccinator muscle
  • Musculus digastricus (venter posterior)
  • Stylohyoid muscle
  • stapedius muscle
  • Reichert cartilage
  • Stapes
  • Processus styloideus
  • Os hyoideum (cornu minus, corpus ossis hyoidei)
  • Ligamentum stylohyoideum
  • Arteria stapedia
  • Arteria hyaloidea (if applicable)
  • Arteria pharyngea ascendens incl. Arteria tympanica inferior
3
  • Glossopharyngeal nerve with tympanic nerve
  • Musculus stylopharyngeus
  • Musculus constrictor pharyngis superior et medius (partially)
  • Salpingopharyngeal muscle
  • Musculus palatoglossus
  • palatopharyngeal muscle (partial)
  • Os hyoideum (cornu majus)
  • Common carotid artery, internal carotid artery
4
  • Laryngeal nerve superior to the vagus nerve
  • Accessory nerve
  • Musculus constrictor pharyngis medius et inferior (partially)
  • Musculus levator veli palatini
  • Musculus cricothyroideus
  • Cartilago thyroidea (upper half)
  • Cartilago cuneiformis
  • Aortic arch (partial)
  • Arteria subclavia dextra (partial)
5
  • Accessory nerve (if applicable)
  • sternocleidomastoid muscle, if applicable
  • trapezius muscle, if applicable
6
  • Laryngeal recurrent nerve of the vagus nerve
  • Musculus constrictor pharyngis inferior (partial)
  • internal laryngeal muscles
  • Cartilago thyroidea (lower half)
  • Cartilago arytenoidea
  • Cartilago corniculata
  • Cartilago cricoidea
  • Trachea (partial), if applicable
  • Arteriae pulmonales
  • Ductus arteriosus
  • Truncus pulmonalis (probably more from the aortic sack)

The following derivatives arise from the endoderm of the 5 pharyngeal pouches:

  • auditory tube
  • Primary tympanic cavity
  • Tympanic membrane (partial)
  • Tonsilla palatina
  • Glandula parathyreoidea
  • Thymus
  • C-cells of the thyroid gland

The ectoderm of the first pharyngeal furrow develops into the external auditory canal and parts of the tympanic membrane. The second to fourth pharyngeal furrows are displaced into the cervical sinus and obliterate.

The ectoderm and entoderm of the first gill arch also develop into the mucosa and glands of the anterior two-thirds of the tongue. The posterior third develops from the fusion site of the second and third gill arches (copula) and parts of the fourth gill arch. It consists only of endodermal parts.

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