Aorta: anatomy and congenital anomalies

1. NORMAL ANATOMY AND
CONGENITAL ANOMALIES OF
AORTA
Dr. Milan Silwal
1st year Resident
MD Radiodiagnosis, NAMS

2. Aorta
• Commence at the base(upper end) of the left
ventricle (aortic annulus)
• Diameter =30mm at commencement.
• Parts : -ascending aorta
-arch of aorta
-descending-thoracic aorta
-abdominal aorta

3. THE THORACIC AORTA
• extends from the aortic valve to the diaphragm
and divided into:
1. Ascending aorta
2. Arch of Aorta
3. Descending aorta

4. The Ascending Aorta
• Begins at the aortic annulus( approx. 3cm in diameter) at the level
of the lower border of the third costal cartilage
• ascends to the right, arching over the pulmonary trunk to lie behind
the upper border of the second right costal cartilage
• Aortic sinuses – three localized dilatations above the cusps of the
aortic valve
anterior – right coronary artery
left posterior – left coronary artery
right posterior – non coronary sinus
• Length= 5cm

7. Arch of aorta
• Continuation of ascending aorta, at the level of upper border of 2nd
right sternocostal joint
• First ascends back and to the left over anterior surface of trachea
and behind the manubrium sterni
• Arches over the left mainstem bronchus and pulmonary artery
• Finally ends on the left side of T4 vertebral body at the level of 2nd
left costal cartilage, where it continues as descending thoracic aota
• Length=5cm

9. • Superiorly are the three branches of the arch
that are crossed anteriorly by the left
brachiocephalic vein
• The branches of the arch of the aorta are the
brachiocephalic, the left common carotid and
the left subclavian arteries

10. Braches of Aortic Arch
• Right brachiocephalic/ Innominate
• Left Common Carotid
• Left Subclavian

11. • The following other arteries may also arise
from the aortic arch:
1. one or both bronchial arteries ,
2. thyroidea ima artery,
3. inferior thyroid artery,
4. internal thoracic artery

12. Aortic Isthmus
• junction of the arch of the aorta
and the descending aorta just distal
to the origin of the left subclavian
artery
• At this site the ligamentum
arteriosus joins the inferior
concavity of the aortic arch to the
main pulmonary artery
• The aorta is fixed at this point and is
thus prone to injury with the
shearing forces of blunt trauma

13. Descending thoracic aorta
• Lies in posterior mediastinum
• Begins at T4 vertebral lower border
• Ends at T12 level in diaphragmatic aortic orifice
• Caliber=2.5cm at origin
• The aortic arch ends and the descending thoracic aorta begins
immediately beyond the origin of the left subclavian artery
• The descending aorta passes inferiorly through the posterior
mediastinum to the left of the spinal column

14. Relations
1. Anterior (above downwards)
-left pulmonary hilum
-left atrium
-oesophagus
2. Posterior
-vertebral column
-hemiazygous vein

15. 3. Left lateral-pleura and lung
4. Right lateral-azygous vein
-thoracic duct
-oesophagus

17. The branches of the descending aorta
are as follows:
• Lower Nine pairs of posterior intercostal arteries and a pair of subcostal
arteries arise from the posterior aspect of the descending aorta to run in
the neurovascular grooves of the third to twelfth ribs
(Upper two posterior intercostal arteries are supplied by superior intercostal arteries from
the costocervical bracnch of the subclavian artery)
• These anastomose with the anterior intercostal arteries (AIA)
- upper six AIAs – supplied by the internal thoracic branch of the
subclavian arteries
- next three AIAs – supplied by the musculophrenic artey , the
continuation of the internal thoracic artery
The lower two spaces have no anterior intercostal arteries
• The intercostal arteries give rise to radicular and radiculomedullary
arteries to the spinal cord and its nerve roots

19. • Two to three bronchial arteries, the origins of which are
variable
• The right bronchial artery usually arises from the third
posterior intercostal artery and the two left bronchial
arteries from the aorta itself
• The upper left usually arises opposite T 5 and the lower left
bronchial artery below the left main bronchus
Variations - 2 left and one right(40%)
- 2 left and 2 right(20%)
- 1 left and 2 right(10%)

21. • Four to five oesophageal branches arise from the front of the
aorta
• Mediastinal branches
• Phrenic branches to the upper part of the posterior diaphragm
(which receives most of its blood supply by inferior phrenic
arteries that arise from the abdominal artery)
• Pericardial branches to the posterior pericardium

22. THE ABDOMINAL AORTA

23. Abdominal Aorta
• Begins at the aortic hiatus of the diaphragm
(D12)
• Descends in front of the vertebral column,
commonly a little to the left of the middle line
• Ends to bifurcation at L4 by dividing into the
two common iliac arteries

24. Dimension:
• Normal value quite broad
• Internal diameter at origin: ~25mm
• Gradually tapers and at bifurcation: ~15-
20mm
• It should not exceed 30mm

25. Relations
• Anteriorly:
– The branches of the celiac artery
and the celiac plexus
– Lesser omentum and stomach
– splenic vein
– pancreas
– left renal vein
– inerior part of the duodenum
– mesentery
– Aortic plexus
• Posteriorly:
– separated from the lumbar
vertebræ and intervertebral
fibrocartilages by the anterior
longitudinal ligament and left
lumbar veins

26. • On the right side:
– Azygos vein
– cisterna chyli
– thoracic duct
– right crus of the diaphragm
– the inferior vena cava
• On the left side:
– Left crus of the diaphragm
– The left celiac ganglion
– The ascending part of the
duodenum
– Some coils of the small intestine

27. Branches
• The branches of the abdominal aorta may be
divided into three sets:
– Visceral
– parietal
– terminal

28. VISCERAL BRANCHES
Unpaired
Celiac
Superior Mesenteric
Inferior Mesenteric

29. Visceral Branches…
Paired
Middle Suprarenals
Renals
Gonadal :Testicular/Ovarian

30. Parietal branches:
• Paired:
– Inferior phrenics
– Lumbar
• Unpaired:
– Median sacral

31. Terminal Branches
• Common iliacs - Right and left

32. (A) aorta
(B) right renal artery.
(C)terminal branches of
right renal artery
(D) left renal artery
(E). Lumbar segmental
artery (Third)
(F) right common iliac
artery
(G Median sacral artery.
(H) The left external iliac
artery
(J) left internal iliac artery

34. Celiac artery
• Short thick trunk
• ~1.25 cm in length
• Arises from the front of the aorta, just below
the aortic hiatus of the diaphragm (T12/ L1)
• Course: passes horizontally forward

35. • divides into three large
branches,
– the left gastric,
– the hepatic,
– and the splenic;
– it occasionally gives off
one of the inferior phrenic
arteries

36. Left Gastric Artery
• The smallest of the
three branches
• Distributes branches to
the
– esophagus
– cardiac part of the
stomach,
– both surfaces of the
stomach and
anastomoses with the
right gastric artery

37. Hepatic Artery:
• Size:
– In adult -intermediate in
size between the left
gastric and splenic
– In fetus - it is the largest
of the three branches of
the celiac artery

38. Branches:
• Right Gastric:
Anastomoses with left
gastric
• Gastroduodenal
– Right Gastroepiploic
(anastomoses with left
gastroepiplioic artery)
– Superior
Pancreaticoduodenal
(anastomoses with inferior
pancreaticoduodenal artery)
• Cystic – usually from right
hepatic

39. Splenic artery:
• Largest branch
• Runs horizontally towards
left along the upper border
of pancreas
• Reaches the hilum of spleen
• Then divides into 5-7
branches

40. Branches:
• Pancreatic branches
– Supply body and tail of
pancreas
• 5-7 short gastric arteries
– Supply fundus of stomach
• Left gastroepiploic artery
– Anastomoses with right
gastroepiploic artery
– Supplies stomach and greater
omentum

41. Superior mesenteric artery:
• Arises from front of
aorta
• ~1.25cm below celiac
artery
• At the level of L1

42. Superior mesenteric artery
• Initially lies posterior to the
body of pancreas
• Then in front of the uncinate
process
• Crosses the third part of
duodenum
• Enters the root of mesentery
and runs between its two
layers
• Terminate in right iliac fossa
by anastomosing with
branches of iliocolic artery

43. Supply:
• Derivatives of mid gut
– Lower part of duodenum below the opening of the
CBD
– Jejunum
– Ileum
– Appendix
– Caecum
– Ascending colon
– Right 2/3rd of transverse colon
– Lower 1/3rd of head of pancreas

44. 5 branches:
Middle colic
Inferior
pancreaticoduode
nal
Right colic
Iliocolic
Jejunal and ileal

45. Inferior mesenteric artery:
• Arises from anterior
aspect of aorta at L3 level
• It is the artery of hind gut
– Left 1/3rd of transverse
colon
– Splenic flexure
– Descending colon
– Sigmoid colon
– Rectum
– Upper part of anal canal

46. Branches:
• Left colic:
– Divides into ascending and
descending branches
– Ascending branch anastomoses with
middle colic artery
– Descending branch anastomoses
with highest sigmoid artery
• Sigmoid branches:
– 2-3 in No.
– Supply lower part of descending
colon and sigmoid colon
• Superior rectal artery:
- Supplies rectum and upper half
of anal canal

47. Renal arteries:
• Arise from aorta at the
level of L1 or L2
• Divides into two rami:
– Anterior
– Posterior
• Each rami divides into
segmental branches
which then divide into
lobar branches leading
to interlobar, arcuate,
and interlobular arteries

48. 1. Abdominal
Aorta.
2. Right Renal
Artery.
3. Left Renal
Artery

49. Renal artery variations
• Accessory renal arteries: common; occur in ~30% of
the population
• Aberrant renal arteries: enter via the renal capsule
rather than the hilum
• Early branching (or prehilar branching): occurs in ~10%
of the population
– occurs within 1.5-2.0 cm of origin in the left renal artery or
in the retrocaval segment of the right renal artery
– important to recognise in renal transplant for successful
anastomoses

50. Gonadal artery:
• Testicular/ ovarian
• Arises at L2 level
• Testicular artery passes
through inguinal canal as
internal spermatic artery
and supplies testis
• Ovarian artery passes along
infundibulopelvic ligament,
supplies ovary and fallopian
tube and anastomoses with
branches of uterine artery

51. Lumbar arteries:
- Four pairs opposite the
body of upper 4 lumbar
vertebra.
- Fifth pair is usually
represented by the
lumbar branch of
iliolumbar arteries, but
may occasionally arise
from the median sacral
artery.

52. Median sacral artery
– Represents the
continuation of the
primitive dorsal aorta
– Supply the sacrum and
coccyx
– Anastomose with
iliolumbar and lateral
sacral artery

53. Common iliac arteries
• Terminal branches of abdominal aorta at
lower border of L4
• Right common iliac=5cm and left common
iliac= 4cm in length
• Right and left common iliac arteries divide
between the L5 and S1 vertebrae into
external and internal iliac artery

54. Abdominal aorta branches : summary

55. Celiac artery and its branches

56. Superior mesenteric artery and its branches

57. Inferior mesenteric artery and its branches

58. Variants of Celiac Trunk
LGA
SACA
SMA
HA
Type 1 (93%)
HGSp trunk+ SM
LGA
SACA
SMA
HA
Type 2 (1%)
LGA arises from Aorta

59. Variants of Celiac Trunk
Type 3 (0.5%)
SA arises from Aorta
Type 4(0.5%)
HA arises from Aorta
LGA
CA
SMA
HA
LGA
CA
SMA
HA SA SA

60. Variants of Celiac Trunk
Type 5 (4%)
LGA and SA arise from CA
HA arises from SMA
Type 6 (0.5%)
A common trunk for both CA and SMA
LGA
CA
SMA
HA
LGA
CA
SMA
HA
SA
SA

61. Variants of hepatic artery
Type A
HA arise from CA
LGA
CA SA
SMA
HA
Type B (4%)
HA arises from SMA
LGA
SAHA
SMA

62. CONGENITAL ANOMALIES

63. Embryology
• Six pairs of arterial
arches develop
between paired ventral
and dorsal aorta from
approx. day 26 in utero
• They are not all present
at the same time and
normally the left fourth
arch develops into the
aortic arch

65. • Double Arch:
• Double Arch with Atretic Segment:
• Normal Left Arch:
• Right Arch with mirror branching:
• Left Arch with aberrant right
subclavian artery:
• Right Arch with aberrant left
subclavian artery:

66. Innominate artery compression
syndrome
• In children the brachiocephalic (innominate)
artery is located more to the left and may
compresses the trachea anteriorly.

67. 1. Double aortic arch
• the result of persistence of
the embryologic double
arch, is the most common
cause of a symptomatic
vascular ring.
• much less commonly
associated with congenital
heart anomalies.
• the right arch is generally
higher and larger than the
left arch

68. • The descending arch is on the left side in most
patients.
• the size of the left aortic arch is variable, and
the effect of a relatively atretic left arch on
tracheal diameter often determines the
symptoms

69. Double Aortic Arch…
• Complete ring encircles
esophagus and trachea.
• Four vessel sign.

70. Figure 1: Chest radiography shows bilateral aortic notches at the level of
aortic arch, suggesting aortic arch anomaly. Right aortic arch (large arrow)
and left aortic arch (small arrow) can be seen

71. 2. Double Arch with Atretic Segment
• Left arch is very small
and has atretic posterior
segment.
• Still a four vessel sign.

72. 3. Right Arch Mirror Image
• has 98% association with
congenital heart disease,
the vast majority being
Tetralogy of Fallot
• Generally asymptomatic
• Posterior part of the left
arch involutes
• The two brachiocephalic
vessels on the left form the
left innominate artery

73. 4. Left arch with aberrant right
subclavian artery
• Also known as arteria
lusoria.
• Most common arch
anomaly being found in
approximately 1% of
individuals. It is rarely
symptomatic.
• The right subclavian artery
arises as a fourth branch of
the arch and must cross the
mediastinum to reach the
right arm.

74. • It crosses behind the esophagus in 80% of
cases, between the trachea and esophagus in
15%, and anterior to the trachea in 5%
• A dilatation at the origin of the anomalous
vessel is termed a diverticulum of Kommerell.
If large, it may cause significant posterior
impression on the esophagus and result in
dysphagia lusoria

76. 5. Right Arch with Aberrant left subclavian
• An obstructing arch anomaly
• The first branch of the aorta is the left
common carotid, followed by the right
subclavian artery and the right
common carotid
• This also is a true ring
• The ligamentum ductus arteriosus
between the arch at the level of the
left subclavian artery and the left
pumonary artery completes the ring
• If this ligament is very short, there will
be a lot of compression

77. The cervical aortic arch
• The cervical aortic arch is an uncommon
anomaly in which the aortic arch extends into
the soft tissues of the neck.
• Patients with this anomaly are generally
asymptomatic, but they can present with
dysphagia, stridor, or a pulsatile neck mass

78. • Aneurysms involving a cervical aortic arch have
been reported, with several cases of aneurysmal
rupture.
• The ascending aorta is elongated with a high,
transverse arch and redundant descending
portion distal to the kink.
• A cervical aortic arch develops most likely from
the persistence of the embryonic third aortic
arch instead of the fourth

80. Coarctation of the aorta
• A primary abnormality of the media with eccentric narrowing of
the aortic lumen due to infolding of the aortic wall
• Associated with bicuspid aortic valve (75%), cerebral aneurysms (5-
10%) and Turner syndrome (20% have coarctation)
• Patients may be asymptomatic in a setting of a non-severe stenosis
• Children and adults can present with angina pectoris and leg
claudication
• On clinical examination, diminished femoral pulses and differential
blood pressure between upper and lower extremities may be noted

82. Two types:
• infantile (pre-ductal) form:
– typically with a more discrete area of constriction just
proximal to the ductus.
– blood supply to the descending aorta is via the patent
ductus arteriosus
• adult (juxta-ductal, post-ductal or middle aortic) form:
– short segment abrupt stenosis of the post-ductal
aorta
– due to thickening of the aortic media and typically
occurs just distal to the ligamentum arteriosum

83. Radiographic features
• Figure of 3 sign
• Inferior rib notching (Roesler sign)
- unusual in patients <5 ys of age
- usually the 4th to 8th ribs
occasionally 3rd to 9th ribs
(1st and 2nd ribs never involved)
• may also show evidence of left
ventricular hypertrophy

85. Pseudocoarctation
• Pseudocoarctation (aortic kink) of the thoracic aorta is a
misnomer since it is a mild form of coarctation
• The infolding occurs near the ligamentum arteriosum
similar to the localized form of coarctation
• Patients are asymptomatic due to the lack of a
hemodynamically significant stenosis (less than 10 mm Hg
pressure gradient across the kink)
• There is a similar incidence of associated bicuspid aortic
valve.

86. THANK YOU!

87. REFERENCES
• Anatomy for Diagnostic Imaging, 3rd edition by
Stephanie Ryan et al
• Fundamentals of Diagnostic Radiolology 4th
edition, by William E Brant et al
• Radiology assistant