The aortic arches or pharyngeal arch arteries (previously referred to as branchial arches in human embryos) are a series of six paired embryological vascular structures which give rise to the great

arteries An artery (plural arteries) () is a blood vessel in humans and most animals that takes blood away from the heart to one or more parts of the body (tissues, lungs, brain etc.). Most arteries carry oxygenated blood; the two exceptions are the pu ...

of the neck and head. They are ventral to the

dorsal aorta The dorsal aortae are paired (left and right) embryological vessels which progress to form the descending aorta. The paired dorsal aortae arise from aortic arches that in turn arise from the aortic sac. The primary dorsal aorta is located deep ...

and arise from the

aortic sac The aortic sac or aortic bulb is a dilated structure in mammalian embryos, lined by endothelial cells and is the most distal part of the truncus arteriosus. It is the primordial vascular channel from which the aortic arches arise (and eventually th ...

. The aortic arches are formed sequentially within the

pharyngeal arch The pharyngeal arches, also known as visceral arches'','' are structures seen in the embryonic development of vertebrates that are recognisable precursors for many structures. In fish, the arches are known as the branchial arches, or gill arche ...

es and initially appear symmetrical on both sides of the embryo, but then undergo a significant remodelling to form the final asymmetrical structure of the great arteries.

Structure

Arches 1 and 2

The ''first'' and ''second arches'' disappear early. A remnant of the 1st arch forms part of the maxillary artery, a branch of the external carotid artery. The ventral end of the second develops into the

ascending pharyngeal artery The ascending pharyngeal artery is an artery in the neck that supplies the pharynx, developing from the proximal part of the embryonic second aortic arch. It is the smallest branch of the external carotid and is a long, slender vessel, deeply se ...

, and its dorsal end gives origin to the stapedial artery, a vessel which typically atrophies in humans but persists in some mammals. The stapedial artery passes through the ring of the

stapes The ''stapes'' or stirrup is a bone in the middle ear of humans and other animals which is involved in the conduction of sound vibrations to the inner ear. This bone is connected to the oval window by its annular ligament, which allows the foo ...

and divides into supraorbital, infraorbital, and mandibula branches which follow the three divisions of the

trigeminal nerve In neuroanatomy, the trigeminal nerve ( lit. ''triplet'' nerve), also known as the fifth cranial nerve, cranial nerve V, or simply CN V, is a cranial nerve responsible for sensation in the face and motor functions such as biting and chew ...

. The infraorbital and mandibular branches arise from a common stem, the terminal part of which anastomoses with the

external carotid The external carotid artery is a major artery of the head and neck. It arises from the common carotid artery when it splits into the external and internal carotid artery. External carotid artery supplies blood to the face and neck. Structure Th ...

artery. On the obliteration of the stapedial artery, this anastomosis enlarges and forms the internal maxillary artery; branches formerly of the stapedial artery are subsequently considered branches of the internal maxillary artery. The common stem of the infraorbital and mandibular branches passes between the two roots of the

auriculotemporal nerve The auriculotemporal nerve is a branch of the mandibular nerve (CN V3) that runs with the superficial temporal artery and vein, and provides sensory innervation to various regions on the side of the head. Structure Origin The auriculotempor ...

and becomes the

middle meningeal artery The middle meningeal artery ('' la, arteria meningea media'') is typically the third branch of the first portion of the maxillary artery. After branching off the maxillary artery in the infratemporal fossa, it runs through the foramen spinosum t ...

; the original supraorbital branch of the stapedial is represented by the orbital twigs of the middle meningeal. Note that the external carotid buds from the horns of the aortic sac left behind by the regression of the first two arches.

Arch 3

The ''third aortic arch'' constitutes the commencement of the internal carotid artery, and is therefore named the carotid arch. It contributes to the common carotid artery and the proximal portion of the internal carotid artery.

Arch 4

Also known as the systemic arch. The ''fourth right arch'' forms the most proximal segment of the right subclavian artery, as far as the origin of its internal thoracic branch. The ''fourth left arch'' forms a part of the arch of the aorta, between the origin of the left common carotid and the

left subclavian In human anatomy, the subclavian arteries are paired major arteries of the upper thorax, below the clavicle. They receive blood from the aortic arch. The left subclavian artery supplies blood to the left arm and the right subclavian artery supplie ...

arteries.

Arch 5

The ''fifth arch'' either never forms or forms incompletely and then regresses.

Arch 6

The proximal part of the ''sixth right arch'' persists as the proximal part of the right

pulmonary artery A pulmonary artery is an artery in the pulmonary circulation that carries deoxygenated blood from the right side of the heart to the lungs. The largest pulmonary artery is the ''main pulmonary artery'' or ''pulmonary trunk'' from the heart, and ...

while the distal section degenerates; The ''sixth left arch'' gives off the left

and forms the

ductus arteriosus The ''ductus arteriosus'', also called the ''ductus Botalli'', named after the Italian physiologist Leonardo Botallo, is a blood vessel in the developing fetus connecting the trunk of the pulmonary artery to the proximal descending aorta. It a ...

; 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 arteriosum. The

connects at a junction point that has a low pressure zone (commonly called

Bernoulli's principle In fluid dynamics, Bernoulli's principle states that an increase in the speed of a fluid occurs simultaneously with a decrease in static pressure or a decrease in the fluid's potential energy. The principle is named after the Swiss mathematici ...

) created by the inferior curvature (inner

radius In classical geometry, a radius ( : radii) of a circle or sphere is any of the line segments from its center to its perimeter, and in more modern usage, it is also their length. The name comes from the latin ''radius'', meaning ray but also the ...

) of the artery. This low pressure region allows the artery to receive ( siphon) the blood flow from the pulmonary artery which is under a higher pressure. However, it is extremely likely that the major force driving flow in this artery is the markedly different arterial pressures in the pulmonary and systemic circulations due to the different arteriolar resistances.

His His or HIS may refer to: Computing * Hightech Information System, a Hong Kong graphics card company * Honeywell Information Systems * Hybrid intelligent system * Microsoft Host Integration Server Education * Hangzhou International School, in ...

showed that in the early embryo the right and left arches each gives a branch to the

lungs The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side ...

, but that later both pulmonary arteries take origin from the left arch.

Clinical significance

Most defects of the great 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 Aberrant subclavian artery, or aberrant subclavian artery syndrome, is a rare anatomical variant of the origin of the right or left subclavian artery. This abnormality is the most common congenital vascular anomaly of the aortic arch, occurring i ...

; 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 The trachea, also known as the windpipe, is a cartilaginous tube that connects the larynx to the bronchi of the lungs, allowing the passage of air, and so is present in almost all air- breathing animals with lungs. The trachea extends from the ...

and

esophagus The esophagus ( American English) or oesophagus (British English; both ), non-technically known also as the food pipe or gullet, is an organ in vertebrates through which food passes, aided by peristaltic contractions, from the pharynx to ...

, which may constrict these organs, although usually with no clinical symptoms. * A

double aortic arch Double aortic arch is a relatively rare congenital cardiovascular malformation. DAA is an anomaly of the aortic arch in which two aortic arches form a complete vascular ring that can compress the trachea and/or esophagus. Most commonly ther ...

; 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 difficulty 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. *

Right-sided aortic arch Right-sided aortic arch is a rare anatomical variant in which the aortic arch is on the right side rather than on the left. During normal embryonic development, the aortic arch is formed by the left fourth aortic arch and the left dorsal aorta. I ...

Patent ductus arteriosus ''Patent ductus arteriosus'' (PDA) is a medical condition in which the ''ductus arteriosus'' fails to close after birth: this allows a portion of oxygenated blood from the left heart to flow back to the lungs by flowing from the aorta, which has ...

Coarctation of the aorta Coarctation of the aorta (CoA or CoAo), also called aortic narrowing, is a congenital condition whereby the aorta is narrow, usually in the area where the ductus arteriosus (ligamentum arteriosum after regression) inserts. The word ''coarctation' ...

Additional images

File:Gray474.png, Diagram showing the origins of the main branches of the carotid arteries.

References

External links

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* {{Authority control Embryology of cardiovascular system Pharyngeal arches