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Structure

Aorta

Not medically reviewed · Content last updated · 2 min read ·

This is the date the draft was written, not a medical review date.

The aorta is the largest artery and the main conduit of the systemic circulation, running from the left ventricle to its bifurcation into the common iliac arteries at about L4. It has ascending, arch, descending thoracic and abdominal parts.

Terminologia Anatomica (Latin): Aorta · Open in the 3D atlas

Location

The ascending aorta starts at the aortic valve inside the pericardium; the arch passes over the left main bronchus; the descending aorta lies in the posterior mediastinum, crosses the diaphragm at T12 (aortic hiatus) and continues in the retroperitoneum slightly left of the midline.

Structure

The root has three sinuses (right, left, non-coronary) and the sinotubular junction. The arch gives the brachiocephalic trunk, left common carotid and left subclavian arteries, with the ligamentum arteriosum at the isthmus. The wall has intima, a thick elastic media and an adventitia; the abdominal aorta gives coeliac, superior mesenteric, renal, gonadal, inferior mesenteric and lumbar branches.

Blood supply

The outer part of the media and the adventitia are supplied by vasa vasorum; the inner media is nourished by diffusion from the lumen. Disease of the vasa vasorum contributes to medial degeneration.

Innervation

Autonomic aortic plexuses supply smooth muscle tone. Baroreceptors in the arch (aortic nerve, joining the vagus) and aortic bodies (chemoreceptors) provide reflex input to the medulla.

Function

Conducts blood at high pressure to all regional arteries and, through its elastic recoil (Windkessel effect), converts pulsatile ejection into more continuous flow during diastole.

Clinical correlations

Abdominal aortic aneurysm is most often infrarenal and linked to atherosclerosis and smoking; screening policies differ by country. Acute dissection begins with an intimal tear (Stanford type A involves the ascending aorta, type B does not) and presents with tearing chest or back pain. Coarctation is usually juxtaductal, and blunt trauma tends to rupture the aorta at the isthmus.

Common exam points

  • Branches of the arch in order: brachiocephalic trunk, left common carotid, left subclavian.
  • Aortic hiatus T12, oesophageal hiatus T10, caval opening T8.
  • Aortic bifurcation at L4; coeliac trunk at T12, SMA at L1, renal arteries at L1 to L2, IMA at L3.
  • Isthmus (near the ligamentum arteriosum) is the usual site of traumatic rupture and of juxtaductal coarctation.
  • Stanford type A dissection involves the ascending aorta and is a surgical emergency; type B does not involve it.

References

  1. Drake RL, Vogl AW, Mitchell AWM. Gray's Anatomy for Students. Elsevier — Tier 3 (textbook)
  2. Moore KL, Dalley AF, Agur AMR. Clinically Oriented Anatomy. Wolters Kluwer, 8th edition (2018) — Tier 3 (textbook)
  3. Loscalzo J, et al.. Harrison's Principles of Internal Medicine. McGraw-Hill, 21st edition (2022) — Tier 3 (textbook)
  4. Kumar V, Abbas AK, Aster JC. Robbins and Cotran Pathologic Basis of Disease. Elsevier, 10th edition (2020) — Tier 3 (textbook)

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