The Aortic ArchesThe Aortic Arches

Embryonic Blood VesselsEmbryonic Blood Vessels By the beginning of the By the beginning of the 4th 4th

weekweek, an extensive network of , an extensive network of blood vessels is formed blood vessels is formed throughout the embryonic throughout the embryonic bodybody

The heart begins to beat on The heart begins to beat on 2121stst or 22 or 22ndnd day day, and blood , and blood begins to circulate.begins to circulate.

This makes the This makes the CVSCVS to be the to be the first system in the body to first system in the body to reach the functional statereach the functional state

The embryonic heartbeat can The embryonic heartbeat can be detected ultrasono-be detected ultrasono-graphically during the graphically during the 55thth weekweek

The main embryonic The main embryonic vessels are the paired vessels are the paired dorsal aortae, dorsal aortae, which which receive blood from receive blood from the heart and the heart and distribute it to body distribute it to body tissuestissues

The dorsal aortae fuse The dorsal aortae fuse caudally during the caudally during the fourth weekfourth week, forming , forming a single median a single median vessel, the vessel, the descending descending aortaaorta..

The descending The descending aortaaorta gives the gives the following branches:following branches: Lateral segmentalLateral segmental Ventral segmentalVentral segmental Dorsal intersegmentalDorsal intersegmental

The caudal end of the The caudal end of the descending aorta descending aorta becomes the becomes the median median sacral arterysacral artery

Lateral Segmental Lateral Segmental ArteriesArteries:: Supply the:Supply the:

DiaphragmDiaphragm KidneysKidneys Adrenal glandsAdrenal glands GonadsGonads

These vessels become These vessels become the the phrenicphrenic, , renalrenal, , middle suprarenalmiddle suprarenal, and , and gonadalgonadal arteries of the arteries of the adult.adult.

Ventral Segmental Ventral Segmental ArteriesArteries:: Supply the:Supply the:

Yolk sac Yolk sac (Vitelline (Vitelline arteries)arteries)

Allantois Allantois (Umbilical (Umbilical arteries)arteries)

Embryonic part of Embryonic part of placenta placenta (Chorionic (Chorionic arteries)arteries)

Vitelline arteriesVitelline arteries:: Supply the yolk sac and Supply the yolk sac and

the primitive gutthe primitive gut Three major arteries Three major arteries

remain as the:remain as the: Celiac trunk Celiac trunk (artery of (artery of

foregut)foregut) Superior mesenteric Superior mesenteric

artery artery (artery of midgut)(artery of midgut) Inferior mesenteric Inferior mesenteric

artery artery (artery of (artery of hindgut)hindgut). .

Umbilical arteries:Umbilical arteries: Pass through the connecting Pass through the connecting

stalk in close association with stalk in close association with the allantoisthe allantois

Become continuous with the Become continuous with the chorionic blood vessels.chorionic blood vessels.

Carry poorly oxygented blood Carry poorly oxygented blood to the placentato the placenta

Derivatives: Derivatives: Proximal partsProximal parts: persist as : persist as

the the superior vesical superior vesical arteriesarteries, which supply the , which supply the urinary bladder urinary bladder

Distal partsDistal parts: obliterate after : obliterate after birth and become the birth and become the median umbilical ligamentsmedian umbilical ligaments

Dorsal intersegmental Dorsal intersegmental arteriesarteries:: Somatic Somatic branchesbranches About About thirty or more pairs thirty or more pairs arise arise

at serial segmental levels, run at serial segmental levels, run between the somitesbetween the somites

Supply the Supply the body wallbody wall, , limbslimbs, , brainbrain and and spinal cordspinal cord..

Derivatives:Derivatives: In In cervical regioncervical region: join to form the : join to form the

vertebral artery. vertebral artery. The The 77thth pair pair contributes to the contributes to the subclavian arteriessubclavian arteries. .

In In thoracic regionthoracic region: become the : become the posterior intercostal arteriesposterior intercostal arteries

In In abdominal regionabdominal region: become the : become the lumbar arteries. lumbar arteries. The The 55thth pair pair remains remains as the as the common iliac arterycommon iliac artery

In In sacral regionsacral region: form the : form the lateral sacral lateral sacral arteriesarteries

Aortic ArchesAortic Arches The aortic arches are a series of The aortic arches are a series of

pairedpaired arterial channels encircling arterial channels encircling the embryonic pharynxthe embryonic pharynx

They:They: Develop in the Develop in the 44thth week week Supply the developing Supply the developing

pharyngeal archespharyngeal arches AriseArise from the from the aortic sacaortic sac RunRun dorsally dorsally,, embedded in the embedded in the

mesenchyme of the pharyngeal mesenchyme of the pharyngeal arches andarches and

TerminateTerminate in the in the right and leftright and left dorsal aortaedorsal aortae

Develop in a Develop in a craniocaudal craniocaudal sequencesequence

There are potentially There are potentially six pairssix pairs, , but the but the fifth pair fifth pair is poorly is poorly developed and disappears soon developed and disappears soon after formationafter formation

Not all the 6 pairs present at the Not all the 6 pairs present at the same timesame time. By the time the 6. By the time the 6thth aortic arches are formed, the 1aortic arches are formed, the 1stst & 2& 2ndnd have disappeared have disappeared

In the region of aortic arches, the In the region of aortic arches, the dorsal aortae remain paired, but dorsal aortae remain paired, but caudal to this region they fuse to caudal to this region they fuse to form a single median vesselform a single median vessel

Aortic --sac

During During week 6 to 8week 6 to 8, the primitive aortic arch , the primitive aortic arch pattern is transformed into the adult arterial pattern is transformed into the adult arterial arrangement of arrangement of carotidcarotid, , subclaviansubclavian, and , and pulmonary pulmonary arteries arteries

Derivatives of Aortic ArchesDerivatives of Aortic Arches

First PairFirst Pair Largely disappearLargely disappear Dorsal part persists Dorsal part persists

as the as the maxillary maxillary arteriesarteries which which supply the ear, teeth supply the ear, teeth and muscles of the and muscles of the eyes and faceeyes and face

May give rise to the May give rise to the external carotid external carotid arteryartery The first arch is obliterated before The first arch is obliterated before

the 6the 6thth arch is formed arch is formed

Second PairSecond Pair

Largely disappearLargely disappear Dorsal part persists Dorsal part persists

as the as the hyoidhyoid and and stapedialstapedial arteries arteries

Third PairThird Pair

Proximal partProximal part: : forms the forms the common common carotid arteriescarotid arteries

Distal partDistal part: : joins the dorsal joins the dorsal aortae to form aortae to form the the internal internal carotid arteriescarotid arteries

Fifth PairFifth Pair

Disappears Disappears completely completely with with NONO vascular vascular derivativesderivatives

The fate of The fate of 4 & 64 & 6thth pairs of aortic pairs of aortic arches differs on the right and left arches differs on the right and left

side side

Fourth PairFourth Pair

RIGHTRIGHT: : Becomes the Becomes the proximal part of proximal part of the the right right subclavian arterysubclavian artery

LEFTLEFT: Forms Forms part of the part of the arch arch of aortaof aorta

Arch of AortaArch of Aorta

Derived as: Derived as: Proximal segmentProximal segment

from from aortic sacaortic sac Middle segmentMiddle segment from from

the the left 4left 4thth aortic arch aortic arch Distal segmentDistal segment from from

the the left dorsal aortaleft dorsal aorta

Subclavian ArterySubclavian Artery

The The rightright subclavian subclavian artery formed from the:artery formed from the: Right Right 44thth aortic arch aortic arch Right Right dorsal aortadorsal aorta & & Right Right 77thth

intersegmental arteryintersegmental artery The The leftleft subclavian subclavian

artery formed from the artery formed from the left left 77thth intersegmental intersegmental arteryartery

Sixth PairSixth Pair RIGHTRIGHT::

• Proximal partProximal part: persists as the : persists as the proximal part of the proximal part of the right right pulmonary arterypulmonary artery

• Distal partDistal part: degenerates: degenerates LEFTLEFT::

• Proximal partProximal part: persists as the : persists as the proximal part of the proximal part of the left left pulmonary arterypulmonary artery

• Distal partDistal part: forms : forms ductus ductus arteriosusarteriosus, a shunt between , a shunt between pulmonary artery and dorsal pulmonary artery and dorsal aortaaorta

Changes in the original aortic arch systemChanges in the original aortic arch system

Obliteration ofObliteration of::

1.1. Most of the Most of the 11stst & 2nd arches & 2nd arches

2.2. 55thth arches arches completelycompletely

3.3. Distal partDistal part of the of the right sixth right sixth archarch

4.4. The The segment of both aortae segment of both aortae lying lying between the 3between the 3rdrd & 4 & 4thth archesarches

5.5. The The segment of right aorta segment of right aorta lying lying between the 7between the 7thth intersegmental artery & the intersegmental artery & the fused dorsal aortaefused dorsal aortae

Relation of recurrent laryngeal Relation of recurrent laryngeal nerves to the aortic arches nerves to the aortic arches

Anomalies of the Anomalies of the Aortic ArchesAortic Arches

Coarctation of AoCoarctation of Aortarta Characterized by Characterized by narrowing of aortanarrowing of aorta More common in malesMore common in males Classified as Classified as PreductalPreductal & & PostductalPostductal

types, but mostly the constriction lies types, but mostly the constriction lies distal to the origin of subclavian artery distal to the origin of subclavian artery opposite the ductus arteriosus opposite the ductus arteriosus ((JuxtaductalJuxtaductal))

Preductal type:Preductal type: Less common. Less common. The narrowing is The narrowing is proximal to the proximal to the

ductus arteriosus. ductus arteriosus. If severe, blood flow to the aorta If severe, blood flow to the aorta

distal to the narrowing (supplying distal to the narrowing (supplying lower body) depends on a lower body) depends on a patent patent ductus arteriosusductus arteriosus, and hence its , and hence its closure can be life-threatening. closure can be life-threatening.

Postductal typePostductal type Most common. Most common. The narrowing is The narrowing is distal to the ductus distal to the ductus

arteriosus. arteriosus. The ductus usually remains open to The ductus usually remains open to

communicate pulmonary artery with the communicate pulmonary artery with the descending aortadescending aorta

Even with an open ductus arteriosus Even with an open ductus arteriosus blood blood flow to the lower body can be impaired. flow to the lower body can be impaired.

Allows development of collateral circulation Allows development of collateral circulation during the fetal period. The collateral during the fetal period. The collateral circulation will develop mainly by branches circulation will develop mainly by branches from both from both subdavian arteries, scapular, subdavian arteries, scapular, internal thoracic and intercostal arteriesinternal thoracic and intercostal arteries. .

It is associated with It is associated with notching of the ribsnotching of the ribs, , hypertension in the upper extremitieshypertension in the upper extremities, and , and weak pulses in the lower extremities. weak pulses in the lower extremities.

Right Arch of AortaRight Arch of Aorta Occurs when theOccurs when the entire right aortic arch entire right aortic arch persistspersists &the&the segment of left dorsal segment of left dorsal aorta distal to the 7th intersegmental aorta distal to the 7th intersegmental artery involutesartery involutes

TYPES: TYPES: Without retropharyngeal component: The DA passes from right pulmonary artery to right arch of aorta. No effect on the trachea & esophagus

With retropharyngeal component: The right arch lies posterior to esophagus. The attachment of DA to distal part of the arch of aorta forms a ring around the trachea & esophagus and may lead to their compression

Double Arch of AortaDouble Arch of Aorta Characterized by a vascular

ring encircling the trachea and esophagus, usually causing compression of both structures.

The degree of compression varies

Usually the right arch is larger and passes posterior to the esophagus

The right common carotid and subclavian arteries arise separately from right arch

RSA LSA

LCCRCC

Patent Ductus ArteriosusPatent Ductus Arteriosus Before birthBefore birth, the , the aortaaorta and and

the the pulmonary artery pulmonary artery are are normally connected by a normally connected by a blood vessel called the blood vessel called the ductus arteriosusductus arteriosus, which is an , which is an essential part of the fetal essential part of the fetal circulation.circulation.

After birthAfter birth, the vessel is , the vessel is supposed to close within a supposed to close within a few days. The obliterated few days. The obliterated vessel forms the vessel forms the ligamentum ligamentum arteriosumarteriosum..

In some babies, the In some babies, the ductus arteriosus ductus arteriosus remains open (patent)remains open (patent)..

This allows blood to This allows blood to flow directly from the flow directly from the aorta into the aorta into the pulmonary artery, pulmonary artery, which can put a strain which can put a strain on the heart and on the heart and increase pressure in the increase pressure in the pulmonary circulationpulmonary circulation

Abnormal Right Subclavian Abnormal Right Subclavian ArteryArtery

May arise from the May arise from the distal part of arch of distal part of arch of aortaaorta

In some cases, the right In some cases, the right subclavian artery arises subclavian artery arises from the descending from the descending aorta and runs behind aorta and runs behind the trachea and the the trachea and the esophagus to supply esophagus to supply the right upper limbthe right upper limb

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