This document discusses various aortic arch anomalies including their embryology, classification, diagnosis and management. It describes abnormalities such as double aortic arch, right aortic arch with mirror branching, retroesophageal right subclavian artery, interrupted aortic arch and more. Diagnostic methods have advanced from barium esophagography to current use of MRI and CT which allow simultaneous visualization of vessels and airways. Surgical division of vascular rings is often required for symptomatic patients.

1. Aortic Arch Anomalies

2.  Hunault in 1735,cited by Moes -wrote pathologic description of
anomalous right subclavian artery.
 Double aortic arch-Hunault 1735
 First report of clinical syndrome of vascular compression-wolman
1939
 Kommerel in 1936 –xray findings of anamolous right sca
 first division of a vascular ring -Gross in 1945
 first successful repair of interrupted aortic arch-Merrill et al. in 1957 .

3. classifications
• Stewert etal and shuford ,syber etal
– Side of aortic arch
– Origin of brachiocephalic vessels
– Site of DA/LA
• Freedom etal-vascular ring/sling/compression
• sissman-Ao.arch position,course,length,size

4. Anatomical Classification
 following anatomic categories:
1)Abnormalities of branching,
2)Abnormalities of arch position including right aortic arch &
cervical aortic arch,
3)Supernumerary arches including double aortic arch and
persistent fifth aortic arch,
4)Interrupted aortic arch
5)Anomalous origin of a pulmonary artery branch from the
ascending aorta or from the contralateral pulmonary artery branch.

5. Embryology
 The specific anomalies better understood through appreciation of
their embryologic origins.
 Development of the aortic arch system - best be described as-
sequential appearance and persistence or regression of 6 paired
vessels connecting the truncoaortic sac of the embryonic heart tube
with the paired dorsal aortae, which fuse to form the definitive
descending aorta.

7. • Fate of the aortic arches:

First pair: A small part forms the maxillary
artery, the rest disappears.
 Second pair: A small part forms the
stapedial & hyoid arteries, the rest
disappears.
 Third pair: forms the common, internal &
external carotid arteries on each side.
 Fourth pair: forms the aortic arch (AA) on
the left side, and the right subclavian (RSC)
artery on the right side.
 Fifth pair: totally disappears.
 Sixth pair: forms the right & left pulmonary
arteries (PA) and the ductus arteriosus (DA).

8. Left and Right Arch Definition
 Left and right aortic arch- refer to which bronchus is crossed by the
arch, not to which side of the midline the aortic root ascends.
 Sidedness determined with Echo or angiography by the branching
pattern of the brachiocephalic vessels.
 General rule – 1st arch vessel contain a carotid artery. contralateral to
Aortic Arch

9. The 3 brachiocephalic br. of the arch are derived from:
- The innominate artery -Rt br. of the truncoaortic sac
- Rt common carotid artery-Rt 3rd embryonic arch
- Rt subclavian -Rt 4th arch and (proximal) Rt dorsal
aorta proximally and Rt 7th ISA distally;
- Lt carotid artery -Lt 3rd aortic arch;
- Lt subclavian artery from Lt 7th ISA.

10. Diagnostic Methods
 1930s, barium esophagography - primary method for diagnosing
arch anomalies.
 In the 1960s and 1970s, angiography became the gold standard .
 In the last 10 to 15 years, MRI and CT, have supplanted angiography
as the gold standard for definitive diagnosis of arch anomalies.
 Both modalities have the advantages of large fields of view and
simultaneous visualization of vessels and airways, and both are
minimally invasive.

11. Edwards hypothetical double arch
concept

12. Clinical Classification
 In addition to the anatomic categorization , arch anomalies divided
according to clinical features as follows:
-Vascular rings;
-Non ring vascular compression of the trachea, bronchi, or
esophagus;
- Noncompressive arch malformations;
-Ductal-dependent arch anomalies including interrupted aortic
arches
- Isolated subclavian, carotid, or innominate arteries.
- Genetic syndromes and associated abnormalities.

13. Vascular Rings
 In this anomaly trachea and esophagus are completely surrounded by
vascular structures.
 The vascular structures need not be patent, e.g., a ligamentum
arteriosum or atretic segment of aortic arch may complete a ring.
 clinical presentation - stridor, pneumonia, bronchitis, or cough .
 Infants may - posture of hyperextension of the neck.
 Less commonly, pts exhibit reflex apnea associated with eating..
 Less commonly in toddlers or older children- swallowing difficulty or
choking .

14.  When all elements of the ring are patent, visualization, especially by
tomographic imaging, is straightforward.
 In cases where the ring is completed by an atretic segment of aorta or
ligamentum arteriosum, those segments cannot be visualized with
current imaging technologies.
 But these rings are recognizable by the presence of one of three
opposite the side of the aortic arch: diverticulum, dimple, or
descending aorta .

15. Normal Left Aortic Arch and variants
 normal left aortic arch crosses the left mainstem bronchus at T5 and
descends left of the midline to the diaphragm and beyond in cases of
visceral situs solitus.
 normal branching pattern has the right innominate artery first.
 branches into the Rt CCA and Rt subclavian arteries
 Lt carotid artery second, and the Lt subclavian artery third.
 Ductus arteriosus or the ligamentum arteriosum joins the aorta distal
to Lt subclavian artery .

16.  2 frequent variants of the Lt aortic arch.
 -1)Common brachiocephalic trunk, in which the right innominate
and left carotid arteries arise from a single origin.
Present in10% of otherwise normal left arches
No consequence,
Some have suggested that innominate artery compression of the
trachea is more frequent when common brachiocephalic trunk is
present.
-

17. 2)Separate origin of the Lt vertebral artery from the aortic arch
proximal to the takeoff of the lt SCA rather than from the SCA .
• Seen in 10% of normal left arches ,No functional significance
•
• should not be confused with anomalous Rt SCA in which there
are also four brachiocephalic vessels .
• Distinguishing feature
3-D MRI of normal variant with separate
origin of left vertebral artery (L Vert) from
the aortic arch

18. Left Aortic Arch with Retroesophageal Rt SCA
 first described by Hunauld in 1735.
 Also called anomalous or aberrant right subclavian artery
 Bayford coined the term dysphagia lusoria•(from the Latin, lusus
naturae, trick of nature).
 The branching pattern
1st branch - Rt CCA
2nd - Lt CCA
3rd - Lt SCA
4th - retroesophageal Rt SCA arising from the
posteromedial aspect of the distal aortic arch

20.  Most common arch anomaly,
 Seen in 0.5% of the general population.
 The incidence in Down syndrome patients with congenital heart
disease is very high at 38% .
 Mostly asymptomatic, with the diagnosis made while imaging for
another condition or at autopsy.

21. assoc
• TOF and left aortic arch-
• COA-
– may arise distal to coarct site. If so:
– BP in RUL and LL does not reflect coarct. Gradient
– Rib notching seen only on left side

22.  Diagnosis and Management
 Since there is no innominate artery, 1st & 2nd branches, (Rt&Lt CA)
similar in size as are the last 2 branches( Lt &Rt SCA)
 Barium esophagography
- Fixed filling defect usually slanting upward to the right
 Angiography
-The diagnosis may sometimes be missed in the AP projection since
the right subclavian may be superimposed on the right carotid artery
in the usual position.
-
Careful single-frame analysis will demonstrate the earlier filling of the
right carotid on an aortic root injection or the earlier filling of the right
subclavian on a descending aortic injection.

23. Barium esophagogram

24. Echocardiography -
-Branching pattern , a nonbifurcating first branch that ascends
toward the right, followed by two successive left-sided vessels
(left carotid and left subclavian arteries) followed by a fourth
branch that heads toward the right but may disappear behind
the trachea.
 MRI
- The retroesophageal course of the subclavian artery is shown
on transverse (axial) cuts.

25. • If symptomatic-
– Division of anamolous RSCA
– Dissection of retroesophageal component if any
– Reanastomosis of vessel
• Establishing flow in RSCA- important.
• Approach in pt with vascular ring-
– right thoracotomy

26. Left Aortic Arch with Retroesophageal
Diverticulum of Kommerell
 Very rare arch anomaly
 1st vascular ring to be diagnosed in life with
barium esophagography by Kommerell
 branching pattern identical to that of the
more common left arch with
retroesophageal right subclavian artery
 The difference is in the caliber of the
proximal subclavian artery .
 significance - is that the abrupt change of
vessel size always indicates the presence of
a ligamentum arteriosum, which completes
a vascular ring.

27. Left Aortic Arch with Right Descending
Aorta and Right Ductus (or Ligamentum)
 Rare arch anomaly, also known as circumflex aortic arch, with a
branching pattern similar to that of left arch with retroesophageal right
subclavian artery.
 The arch itself is retroesophageal; hence the right subclavian artery,
although it may arise as the last arch vessel, is not retro-esophageal .
 The descending aorta is connected by a ductus or ligamentum to the
right pulmonary artery, forming a vascular ring.

29. Left Aortic Arch with Isolated SCA
 Rare anomaly, subclavian artery arises only from the ductus
arteriosus.
 If ductus is patent, the subclavian and vertebral arteries are supplied
from the pulmonary artery.
 When the ductus closes, the subclavian is supplied by retrograde flow
from the vertebral artery via the circle of Willis.
 Embryology
 This occurs with dissolution of the right fourth arch and right dorsal
aorta but persistence of the right sixth arch.

31.  Diagnosis and Management
 in the absence of other anomalies, it may go unrecognized or may
cause vertebrobasilar insufficiency with so-called congenital
subclavian steal.
 With phase-encoded velocity mapping, retrograde flow in the
vertebral artery can be detected on MRI.
 Symptomatic patients are treated by implantation of the subclavian
artery into the aorta.

32. Left Aortic Arch with Cervical Origin of
the Right Subclavian Artery
 Found in pts with TOF, with or
without pulmonary atresia,
 Seen only in patients with 22q11
deletion .
 marker for CATCH 22.
 Normally the right innominate artery
bifurcates into a Rt CCA and Rt
SCA near its origin from the aorta .
 In this Innominate trifurcates in the
neck, giving rise to external and
internal carotids and the SCA, which
then travels caudally back to the
thorax.

33.  Embryology
Rt subclavian artery originates from the third arch, which is more
cephalad than the fourth, gives origin to the subclavian artery in the
neck rather than in the thorax.

34. Right Aortic Arch
 A single aortic arch that crosses over the right main stem bronchus,
passing to the right of the trachea.
 There are four major types of right arch:
(a) with mirror image branching,
(b) with retroesophageal left subclavian artery,
(c) with retro-esophageal diverticulum, and
(d) with left descending aorta.
There are also several infrequently occurring variations.
 Incidence
- InTOF 13% to 34% . Of these-93% mirror image br
-TA -36%-( generally higher than in TOF)
DORV-20% -TGA 3%(assoc with VSD and PS 16%)

35. Right Aortic Arch with Mirror-Image Branching
 1st branch is Lt innominate artery, divides into Lt carotid and Lt
SCA
 2nd Rt carotid, 3rd a Rt subclavian .
 left-right mirror of a normal left aortic arch.
 But ..
 ductus arteriosus (or ligamentum arteriosum) is usually the left-sided
one, arising from the base of the innominate artery rather than from
the aortic arch.
 Therefore ligamentum does not form a vascular ring.
 Almost always associated with congenital intracardiac disease.

37.  Diagnosis and Management
 usually produces no retro-esophageal compression or vascular ring,
 no symptoms produced by the arch itself.
 Diagnosis - usually made during imaging of the assoc congenital
intracardiac disease.
 Diagnosed by distinctive branching pattern in echo and angiography,
and appearance of a right-sided indentation of trachea and esophagus
on plain radiograph and barium esophagography.

38.  No treatment of right aortic arch is required
 It may be helpful for surgeons to know the sidedness of the aortic arch
in certain circumstances.
 For the classical B –T shunt and modified form are best carried out
using the side with an innominate artery.

39. Right Aortic Arch with Retroesophageal
Diverticulum of Kommerell
 Second most common vascular ring after double aortic arch.
 Branching
1st branch -Lt CCA
2nd Rt CCA
3rd Rt SCA
4th - a retro-esophageal vessel from which the Lt SCA arises and the
left ductus arteriosus or ligamentum arteriosum connects.
 This combination of vessels produces a vascular ring.

41.  Diagnosis and Management
 The presenting symptoms are usually that of a vascular ring.
 Appearance of a right aortic arch on a plain CXR .
.
 . Echo -Lt carotid artery arising alone as the first arch vessel,
-Diverticulum followed to the point at which the caliber
changes to that of the smaller subclavian artery.
 Angiography- characteristic branching pattern
- abrupt change in caliber from diverticulum to
subclavian artery.
 MRI - ideal for making this diagnosis
- noninvasive and have the ability to display both vascular and
airway structures.

42.  Most people are asymptomatic.
 Treatment is surgical division of the ductus or ligamentum in those
patients who are symptomatic.
 In those patients undergoing surgery for another lesion, even an
asymptomatic ligamentum should be divided.

43. Right Aortic Arch with Retroesophageal
Left Subclavian Artery
 Arch passing to the right of the trachea
 Sequence of brachiocephalic arteries:
- Left carotid,
- Right carotid,
- Right subclavian,
- and retroesophageal left subclavian .
 This differs from the previous arch in that the proximal left subclavian
artery is not significantly larger in caliber than its more distal portion
(i.e., no aortic diverticulum).
 Therefore, there is no left-sided ductus arteriosus or ligamentum
arteriosum and thus no vascular ring.
 Many of these patients have associated conotruncal anomalies.

44.  Diagnosis and Management
 suspected from barium EsoG -a relatively small posterior indentation
on the esophagus passing upward to the left.
 No vascular ring, the trachea is unaffected except for the slight
leftward deviation .
 Echo- identify the first branch of the aorta as a left carotid artery
 Both MRI and angiography can demonstrate the size of the left
subclavian artery, which distinguishes this lesion from right aortic
arch with retroesophageal diverticulum.
 Since there is no vascular ring, there is usually no need for treatment
other than that of associated anomalies.

45. Right Aortic Arch with Left Descending
Aorta and Left Ductus Arteriosus or
Ligamentum Arteriosum
 Also known as right aortic arch with retroesophageal segment or
circumflex right aortic arch
 Presentation similar to right arch with retro-esophageal diverticulum
 It is the aortic arch that is retroesophageal, not the subclavian artery or
an aortic diverticulum.

46. Diagnosis and Management
The findings on CXR and barium esophagography
may be similar to those in right arch with
retroesophageal diverticulum.
 Differences include a downward to the left instead
of upward to the left orientation of the esophageal
indentation .

47.  Order of brachiocephalic artery branching.
 In the case of right aortic arch with left descending aorta, the first
vessel contains the left carotid artery.
 MRI can avoid some of the pitfalls seen with projection images and
can delineate the entire aorta, its relationship to the trachea .
 Division of the vascular ring when patients are symptomatic.

48. Right Aortic Arch with Retroesophageal
Innominate Artery
 Rare abnormality of the aortic arch system.
 Contrary to the general rule that the first arch vessel contains a
carotid artery contralateral to the aortic arch, in these cases the
sequence of brachiocephalic vessels is right carotid, right subclavian,
retroesophageal left innominate artery .
 The ductus arteriosus or ligamentum arteriosum completes a vascular
ring as it connects the left pulmonary artery with the base of the so-
called innominate artery.

49.  Diagnosis and Management
 Tracheal compression seems to be the rule.
 The important anatomic clues to the diagnosis by any imaging
modality are the presence of a single carotid artery arising from the
proximal aorta.
 The other anomalies with that finding are also rare: Interrupted aortic
arch with interruption between the two carotid arteries and isolated
left carotid or innominate artery.

50. Cervical Aortic Arch
 Rare anomaly ,
 Apex above the clavicle (as high as the C2 ).
 Seperate origin of carotid artery contralateral to arch with seperate
origin if ICA,ECA,SCA on arch side
 2 main subcategories
- Those with anomalous subclavian artery and vascular ring, with
either descending aorta c/l to the arch or retroesophageal diverticulum
-And those with a virtual normal branching pattern.
 The first and larger group usually has a right aortic arch. .
 Separate origin of the vertebral artery from the arch can be seen in
each of the groups.
 The second group typically has a left aortic arch. .
 Stenosis or atresia of the origin of the left subclavian artery is
sometimes seen in either group .

52.  Diagnosis and Management
 Presents as pulsatile masses in the supraclavicular fossa or in the neck.
 In infants, prior to the appearance of mass, presenting signs may be
those of a vascular ring like , stridor, dyspnea, or repeated LRTI.
 In adult, the most likely symptom from a vascular ring is dysphagia.
 In patients with stenosis or atresia of the left subclavian artery and
origin of the ipsilateral vertebral artery distal to the obstruction, a
subclavian steal may exist with CNS symptomatology.
 In the presence of a pulsatile neck mass, brief compression of the
mass results in loss of femoral pulses .

53.  CXR -cervical arch may be suspected by the presence of a widened
upper mediastinum and the absence of the aortic knob.
 Evidence of anterior deviation of the trachea is in favor of the
diagnosis.
 Treatment is necessary if the cervical arch is complicated by arch
hypoplasia, symptomatic vascular ring, or rarely, aneurysm of the
cervical arch itself .

54.  Persistance of both emb.aortic arches with separate origin of CA and
SCA
 therefore-NO innominate artery
 DA-almost always left sided
 A ductus arteriosus or ligamentum may be present-not an essential
element but length may affect-degree of compression
 both arches-usually patent although one is larger
Double Aortic Arch

55. When desc. Aorta is to left of spine- Right arch –larger
–more posterior-75% cases(MC)
The right arch is the more superiorly located.
When desc.aorta is right of spine-left arch –more
posterior-larger-75-85% cases
Rule-desc aorta is contralateral to side of dominant arch
All double aortic arches technically form complete
vascular rings around the trachea and esophagus.
Usually occurs without assoc. CHD.but assoc-22%
cases-TOF ,TGA

56. • Although hypoplasia is common segmental
atresia uncommon usually left.
• Shuford and sybers classification

58.  Embryology
 Persistance of both paired dorsal aortic arches –failure of regression of
right 8th somatic segment of right dorsal aorta
 Right DA regresses in majority
 One of the arch may be atretic- may occur at any segment
 Complete vascular ring
 Peristance of DA on either side not needed to complete vasc.ring like
other forms .
 Double arch with atretic left arch is more commonly associated with
22q11 deletions syndromes than double arch with both widely patent.

62.  Diagnosis and Management
 MC clinically recognised form of vascular ring
 Severely sympto.-infancy-stridor,dyspnea,cough,recurRTI.
 Feed poorly,
 Prefer opisthotonus
 Life threatening episodes of reflex apnea with cyanosis may.
 Routine chest xray often suggests.
 Hyperinflation of either/both lungs
 Barium esophagography-b/l indentations of eso in AP proj
 Large oblique defect(retroeso arch)
 But often not possible to diff from right arch with ana.Left SCA
 Angiography of asc aorta.

63. The diagnosis of double arch with both arches patent
can sometimes be made convincingly from the plain
CXR.
The tracheal air column is indented by the more
superior, right-sided arch and the more inferior left arch.
In the lateral view, the right arch can be seen to indent
the trachea posteriorly.

64.  Confirmation by echo, angiography, or MRI is important to identify
the hypoplastic segment to divide it.
.
 Echo-Suprasternal views-coronal plane-b/l echolucencies of double
arch
.
 MRI-side of dominant arch and patency of minor arch- spatial
relationships of vessels, trachea, and esophagus for surgical planning
.
 Surgical division of the vascular ring in any patient who is
symptomatic with airway or esophageal compression or in a patient
undergoing surgery for intracardiac disease.

65. Persistent Fifth Aortic Arch
 First reported in man by Van Praagh in 1969 as a double-lumen
aortic arch in which both arches appear on the same side of the
trachea.
 In double aortic arch each arch is on the opposite side.
 Subcategorization :
- Double-lumen aortic arch with both lumina patent
-Atresia or interruption of the superior arch with patent inferior
(persistent fifth) arch common origin of all brachiocephalic vessels
from the ascending aorta .

66.  Diagnosis and Management
 Recognized either by angiography or at postmortem examination, with
the appearance of a subway vessel beneath the normal arch.
 Also be seen with MRI , in coronal or off-axis sagittal (candy cane)
sections. .
 In atresia or interruption of the superior arch, there is the appearance
of a truly common brachiocephalic trunk in which all four arch
vessels, including the left subclavian artery, arise from a single vessel
.

67.  At surgery for repair of coarctation of the aorta (distal to the fifth
arch), an atretic strand connecting the left subclavian artery to the
descending aorta may be seen.
 There appears to be no other plausible explanation for such a
branching pattern.
 Without additional coarctation of the existing aorta, these two arch
anomalies alone have no physiologic significance.

68. Interrupted Aortic Arch
 Defined as a complete separation of ascending and descending aorta.
 Celoria and Patton classification
Type A - interruption distal to the left (SCA)subclavian artery
Type B- between carotid and Lt SCA
Type C - between carotid arteries.
A B
C

69. Subcategores
 Interruption distal to that SCA
Without retroesophageal or isolated SCA
With retroesophageal SCA
With isolated SCA
 Interruption between second carotid and ipsilateral SCA
Without retroesophageal or isolated SCA
With retroesophageal SCA (i.e., both carotid arteries proximal,
both subclavians distal)
With isolated SCA
 Interruption between carotid arteries
Without retroesophageal or isolated SCA
With retroesophageal SCA
With isolated SCA

70.  Type A interruptions
-Occur with aorticopulmonary septal defect and intact ventricular
septum
-Seen in patients with transposition of the great arteries and
interrupted aortic arch .
 Type B interruptions
-More common than type A
-Usually have a conotruncal anomaly with normally aligned great
arteries in which there is a large malalignment-type VSD associated
with posterior displacement of the infundibular septum and subaortic
obstruction.
-Pts with DiGeorge syndrome have type B interuption.
 Type C interruption
-Quite rare.

71. In a large series of cases with DiGeorge syndrome
- 43% were found to have type B interruption, and
68% of interrupted arch patients had DiGeorge
syndrome.
This contrasts with truncus arteriosus communis in
which comparable figures were 34% and 33%,
respectively.
 Again it shows the predisposition to 4th arch
abnormality in 22q11 patients.

72.  Diagnosis and Management
 Presentation similar to pts with other ductal-dependent left heart
obstructive lesions, with acute cardiovascular collapse or heart failure
after spontaneous closure of the ductus arteriosus in the first days of
life.
 Initial management - fluid resuscitation, induction and maintenance of
ductal patency with PGE1, and establishment of stable
hemodynamics, with inotropic support .
 Physical findings of pulse discrepancy, depending on branching
pattern, are helpful.
 Absence of all limb pulses suggests type B interruption with
anomalous subclavian artery, i.e., both carotid arteries proximal, both
subclavians distal to the interruption.

73.  2D- echo is the most important tool for diagnostic imaging of
interrupted arch.
 The diagnosis should be suspected from the marked discrepancy in
size between ascending aorta and main pulmonary artery with
subcostal frontal imaging, in the presence of the typical malalignment
type VSD with posterior deviation of the infundibular (conal) septum,
best visualized in the parasternal long-axis view.
 Imaging of the arch from suprasternal or high parasternal for
determination of the branching pattern and patency of the arch

74.  Angiography is used to confirm the diagnosis of interrupted aortic
arch.
 Interruption can be diagnosed consistently by angiography when both
carotid arteries arise proximal to, and both subclavian arteries distal
to, the interruption.
 The wide separation of carotid arteries from descending aorta
unequivocally demonstrates interruption.
 3D reconstruction from MRI can demonstrate the branching pattern
and the separation between proximal and distal aorta .

75. Anomalous Origin of the LPA from RPA
( pulmonary artery sling )
 Origin of the left pulmonary artery from the right pulmonary artery
known as pulmonary artery sling , is a
 Rare anomaly in which the lower trachea is partially surrounded by
vascular structures
 The left pulmonary artery arising as a very proximal branch of the
right loops around the trachea.
 It is the only situation in which a major vascular structure passes
between the trachea and esophagus.
 It usually appears as an isolated abnormality but can be associated
with other congenital cardiac defects, including tetralogy of Fallot.

77.  Diagnosis and Management
 These patients typically present with severe respiratory distress and
stridor
 Barium swallow when classic is diagnostic if one can rule out
mediastinal tumor.
 Echo, angiocardiography, MRI, or CT is usually necessary to ensure
the accuracy of the diagnosis.
 Symptomatic patients should be evaluated by bronchoscopy at the
time of surgical repair because of the frequent association of complete
cartilaginous rings.
 The usual surgical approach is division of the left pulmonary artery
from the right and reanastomosis in front of the trachea.

78. Bovine Aortic Arch Variant in
Humans
 The bovine aortic arch in humans resemble the aortic arch branching
pattern found in the family of ruminant animals, including cattle and
buffalo.
 But bovine aortic arch configuration ascribed to the most common
human aortic arch variants have no resemblance to the aortic arch
branching pattern found in cattle.

79.  This is the human aortic arch branching pattern which has a common
origin for the innominate and left common carotid arteries.
 This pattern has erroneously been referred to as a “bovine arch.”
 The left common carotid artery has a common origin with the
innominate artery, rather than arising directly from the aortic arch as a
separate branch.

80.  A similar but less common variant occurs when the left common
carotid artery originates directly from the innominate artery rather
than as a common trunk .
 Both variants of left common carotid artery origin are called
“bovine-type arch,” .

81. • Thank u