the fate of the arches…
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The fate of the arches…. Trisha J. Oura Radiology Resident 9/21/09. But first…. Early embryogenesis: Thickenings of mesenchyme, ecto and endoderm Mesenchyme migrates ventrolaterally pharngeal bulges Neural and cardiac tissue follow, form concentric hemi-rings. - PowerPoint PPT PresentationTRANSCRIPT
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The fate of the arches…
Trisha J. OuraRadiology Resident
9/21/09
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But first…
• Early embryogenesis:– Thickenings of mesenchyme, ecto and endoderm– Mesenchyme migrates ventrolaterally pharngeal
bulges– Neural and cardiac tissue follow, form concentric
hemi-rings
TW Sadler, Langman’s Medical Embryology, Lippincott, Williams & Wilkins, 2003
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• Enlarged mesoderm stacks (like donuts) to form bilateral pharyngeal (branchial) arches
• Ectoderm clefts (between donuts)• Endoderm pouches (within donuts)
TW Sadler, Langman’s Medical Embryology, Lippincott, Williams & Wilkins, 2003www.gettyimages.com
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• Each pharyngeal arch contains:– Aortic arch– Cartilage core– Muscle– Nerves
BM Patten, BM Carlson, Foundation of Embryology, McGraw-Hill Publishing Co, 1974MSA Kumar, Developmental Anatomy, Tufts, 2009.
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Where did those aortic arches come from?
• Early heart = tube • “S” shaped looping creates
cranial truncus arteriosus• Truncus aortic sac
aortic arches
DM Noden and A DeLahunta, The Embryology of Domestic Animals, Williams & Williams, 1985
KL Moore and TVN Persaud, The Developing Human, Clinically Oriented Embryology, Saunders, 2003
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Now what?
• I, II = disappear early• III = common carotids• IV:
– Right: common brachiocephalic trunk (R subclavian a.)
– Left: arch of aorta• V: transient• VI: pulmonary a.
– Right: no connection to dorsal aorta
– Left: ductus arteriosus (ligamentum arteriosus)
R L
TW Sadler, Langman’s Medical Embryology, Lippincott, Williams & Wilkins, 2003
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Vascular ring anomalies:aberrations, anomalies, and…. avians?• Birds:
– RIGHT IV arch becomes arch of the aorta (vs. left in mammals)
• PRAA (dextroaorta):– mammals = birds– Most common– Poss w/ persistent L CrVC– On radiographs:
• DV/VD = trachea often midline or left
DM Noden and A DeLahunta, The Embryology of Domestic Animals, Williams & Williams, 1985
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PRAA
Normal PRAA
http://cal.vet.upenn.edu/projects/cardiosf/project/embprs/embprs14.htm
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PRAA (Acc 71349)
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Aberrant Subclavians
Right subclavian a.:- Direct from arch of aorta or
w/ the left in bi-subclavian trunk
- Esophagus constricted dorsally w/o complete ring
- R subclavian crosses left right, causes indentation/half ring stricture of esophagus
Normal
Aberrant R. subclavian a.
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Left subclavian a.:- Right IV arch aortic arch (PRAA)- Left IV arch L subclavian- Retains connection to dorsal aorta- Crosses retroesophageally on left - L subclavian constricts esophagus
at heart base
Normal
Anomalous L. subclavian a.
R. subclavian
PRAA
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• Double Aortic Arch– Complete persistence of
both sides of the fourth arch vascular ring anomaly
– Fuse distally to form the descending aorta
– More caudal compression– ONLY vascular ring
anomaly with clinically important tracheal compression
– Treatment: ligate smaller aorta
Normal
Double Aortic Arch
L. subclavian
R. subclavian
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Acc 115803
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References:
1. http://cal.vet.upenn.edu/projects/cardiosf/project/embprs/embprs21.htm
2. MSA. Kumar, Developmental anatomy syllabus, Tufts, 2009.