Aorta

INTRODUCTION:
  • The aorta is the main artery in the human body, originating from the left ventricle of the heart and extending down to the abdomen, where it splits into two smaller arteries (the common iliac arteries).
  • The aorta distributes oxygenated blood to all parts of the body through the systemic circulation
DEVELOPMENT:
  • Angioblastic mesenchyme forms early in 3rd week of development from extraembryonic mesenchyme in the splanchno-pleure (splanchnic/ visceral) of yolk sac, in the body stalk (containing allantois), and in the somatopleure of the choroin.
  • The peripheral cells flattens as a vacular endothelium, whereas central cells transform into primitive RBCs.
  • Angioblastic competence has been demonstrated with in the ventral (splanchnopleuric) of lateral plate mesoderm which forms muscular part of aorta with which the endoderm interacts. However, the notochord, prechordal plate and ectodermal tissue do not contain angiogenic cells.
STRUCTURE:
SECTIONS OF AORTA:
Acc. To Anatomic Compartment:
  1. Thoracic Aorta: From the heart to the diaphragm
  2. Abdominal Aorta:Diaphragm to the aortic bifurcation
  3. Acc. To Course & Direction Of Blood Flow:
Asscending Aorta
  1. Arch Of Aorta
  2. Descending Aorta
  3. Thoracic Abdominal
  4. Ascending aorta
  • Begins at the opening of aortic valve in the left ventricle of the heart.                                           ↓
  • Runs through a common pericardial sheath with the pulmonary trunk (twist around each other, causing the aorta to start out posterior to the pulmonary trun & end by twisting to its right and anterior side)
                        ↓
  • Aortic arch( at the pericardial reflection on the aorta).
  • At root lumen has 3 pockets b/w the cusps of the aortic valve and the wall of the aorta k/as aortic sinuses or the sinuses of Valsalva.
  • The left aortic sinus contains the origin of the left coronary artery and the right aortic sinus likewise gives rise to the right coronary artery. Together, these two arteries supply the heart.
  • The posterior aortic sinus does not give rise to a coronary artery. For this reason the left, right and posterior aortic sinuses are also called left-coronary, right-coronary and non-coronary sinuses
Aortic Arch:
  • Arch of aorta develops from Left fourth aortic arch artery
  • Lies behind manubrium sterni & Loops over the left pulmonary artery and the bifurcation of the pulmonary trunk(remains connected by the ligamentum arteriosum)
  • ↓ (B/w aortic arch and the pulmonary trunk autonomic nerve fibers, cardiac plexus)
  • Crosses the left main bronchus
                        ↓
  • Left vagus nerve, anterior to the aortic arch, gives off recurrent laryngeal nerve, which loops under the aortic arch just lateral to the ligamentum arteriosum
  • Tracheal bifurcation also lies at the level of arch of aorta(25cm from incisor both crosses oesophagus)
  • Branches:
  1. Brachiocephalic trunk
  2. Left common carotid artery
  3. Left subclavian artery.
  • The aortic arch ends and the descending aorta begins at the level of left 2nd costal cartilage between the fourth and fifth thoracic vertebrae
  • Left common carotid artery arising from brachiocephalic trunk is the commonest variation in the arteries arising from the arch of aorta
BRANCHES OF THE THORACIC AORTA
Branches Origin and course
pericardial branches
Bronchial branches Two left bronchial arteries from the thoracic aorta
One right bronchial A- from 3rd posterior intercostal A or upper Lt bronchial A
Esophagealbranches Four or five vessels from the anterior aspect of the thoracic aorta
Mediastinalbranches Several small branches supplying lymph nodes,
vessels, nerves, and areolar tissue in the posterior mediastinum
Posterior intercostal arteries Usually nine pairs- supply lower nine intercostal spaces
(first two spaces are supplied by the supreme intercostal artery-a branch of the costo-cervical trunk)
Superior phrenic arteries Anastomose with the musculophrenic and pericardiacophrenic arteries
Subcostal artery Lowest pair of branches from the thoracic aorta located inferior to rib XII
Thoracic Aorta:
  • Abdominal Aorta:
  • Begins at the aortic hiatus(aorta with thoracic duct & azygous vein) of the diaphragm.
  • Anterior to the lower border of vertebra T-12.
  • Median arcuate ligament passes anterior to the aorta.
BRANCHES OF ABDOMINAL AORTA:
  • 4 pairs of lumbar arteries arise from the aorta & the small fifth pair is usually represented by the lumbar branches of iliolumbar arteries or from the median sacral artery.
Branch Artery Origin Parts supplied
Anterior Celiac trunk Immediately inferior to the aortic hiatus Foregut
Superior mesenteric Immediately inferior to the celiac trunk Foregut
Inferior mesenteric Inferior to the renal arteries Midgut
Paired anterior Testicular or ovari
anarteries
Inferior to the renal arteries Testes in male and
ovaries in female
Lateral& Paired Middle suprarenal Artery Immediately superior to the renal arteries Suprarenal glands
Renal arteries Immediately inferior to the superior
mesenteric artery
Kidneys
Inferior phrenic artery Immediate inferior to aortic hiatus Diaphragm
Posterior paired Lumbar arteries Usually four pairs Posterior abdominal
wall and spinal cord
Posterior Median sacral arteries Just superior to the aortic bifurcation
Terminal Common iliac arteries Bifurcation at the level of L4 It's external branch
Make anastomosis
with superior
epigastric artery
  • Also supplies sequestrated lung lobe
Exam Question 
  • Aorta with thoracic duct & azygous vein crosses through aortic hiatus of diaphragm
  • Brachiocephalic trunk, Left common carotid artery & Left subclavian artery are the branches of arch of aorta
  • Tracheal bifurcation lies at the level of arch of aorta
  • Left common carotid artery arising from brachiocephalic trunk is the commonest variation in the arteries arising from the arch of aorta
  • Celiac trunk, Superior mesenteric & Inferior mesenteric are the branches of anterior part of abdominal aorta
  • Inferior phrenic, Middle Suprarenal, Renal are lateral branches of abdominal aorta
  • External iliac Artery make anastomosis with superior epigastric artery
  • Muscular component of dorsal aorta develops from Lateral plate mesoderm
  • Arch of aorta crosses the esophagus at 25 cm from the incisor teeth
  • Sequestrated Lung lobes are supplied by descending aorta
  • Arch of aorta develops from Left fourth aortic arch artery
  • Aortic arch ends at level of left 2nd costal cartilage
  • Arch of aorta begins and ends at which level T4
  • Aortic arch Lies behind manubrium sterni
  • Ovarian artery is a branch of abdominal aorta
  • Branchiocephalic trunk arise from arch of aorta
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