Aortic arches

This article focuses upon the multiple aortic arches present in the embryo. For the single structure present in the adult, see Aortic arch

The aortic arches or pharyngeal arch arteries are a series of six paired embryological vascular structures which give rise to several major arteries. They are ventral to the dorsal aorta.

Specific arches

Arches 1 and 2

The first and second arches disappear early, but the dorsal end of the second gives origin to the stapedial artery, a vessel which atrophies in humans but persists in some mammals. It passes through the ring of the stapes and divides into supraorbital, infraorbital, and mandibular branches which follow the three divisions of the trigeminal nerve. The infraorbital and mandibular arise from a common stem, the terminal part of which anastomoses with the external carotid.

On the obliteration of the stapedial artery this anastomosis enlarges and forms the internal maxillary artery, and the branches of the stapedial artery are now branches of this vessel.

The common stem of the infraorbital and mandibular branches passes between the two roots of the auriculotemporal nerve and becomes the middle meningeal artery; the original supraorbital branch of the stapedial is represented by the orbital twigs of the middle meningeal.

Arch 3

The third aortic arch constitutes the commencement of the internal carotid artery, and is therefore named the carotid arch.

Arch 4

The fourth right arch forms the right subclavian as far as the origin of its internal mammary branch; while the fourth left arch constitutes the arch of the aorta between the origin of the left carotid artery and the termination of the ductus arteriosus.

Arch 5

The fifth arch disappears on both sides.

Arch 6

The proximal part of the sixth right arch persists as the proximal part of the right pulmonary artery while the distal section degenerates; The sixth left arch gives off the left pulmonary artery and forms the ductus arteriosus; this duct remains pervious during the whole of fetal life, but then closes within the first few days after birth due to increased O₂ concentration. Oxygen concentration causes the production of bradykinin which causes the ductus to constrict occluding all flow. Within 1-3 months, the ductus is obliterated and becomes the ligamentum arteriosus.

His showed that in the early embryo the right and left arches each gives a branch to the lungs, but that later both pulmonary arteries take origin from the left arch.

Great arteries anomalies

Most defects of the grest arteries arise as a result of persistence of aortic arches that normally should regress or regression of arches that normally shouldn't.

• Aberrant subclavian artery; with regression of the right aortic arch 4 and the right dorsal aorta, the right subclavian artery has an abnormal origin on the left side, just below the left subclavian artery. To supply blood to the right arm, this forces the right subclavian artery to cross the midline behind the trachea and esophagus, which may constrict these organs, although usually with no clinical symptoms.
• A double aortic arch; occurs with the development of an abnormal right aortic arch in addition to the left aortic arch, forming a vascular ring around the trachea and esophagus, which usually causes dificutly breathing and swallowing. Occasionally, the entire right dorsal aorta abnormally persists and the left dorsal aorta regresses in which case the right aorta will have to arch across from the esophagus causing difficulty breathing or swallowing.
• Patent ductus arteriosus
• Coarctation of the aorta

Additional images

See also

• Pharyngeal arches

External links

• Embryology at Temple Heart98/heart97b/sld041
• Diagram at University of Michigan
• hednk-008 — Embryology at UNC

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained within it may be outdated.