Topography and syntopy of the abdominal aorta
The abdominal part of the aorta abdominalis originates from the aortic hiatus of the diaphragm (hiatus aorticus) and extends to the level of the IV–V lumbar vertebrae. The vessel lies retroperitoneally on the fascia prevertebralis, positioned to the left of the midline on the anterior surface of the spine.
In terms of syntopy, the following relations are distinguished:
- Anteriorly and superiorly: the vessel is covered by the pancreas, the ascending part of the duodenum, and the root of the mesentery of the small intestine.
- To the left: the left sympathetic trunk and intermesenteric plexus run along it.
- To the right: the large inferior vena cava (v. cava inferior) is located.
Dense adipose tissue containing branches of the abdominal aortic plexus, ganglia, and left lumbar lymph nodes (lateral, preaortic, postaortic, and intermediate) surrounds the aorta.
Branches of the abdominal aorta and bifurcation
Along its course, the arterial trunk gives off numerous branches, which are traditionally divided into two major groups:
- Parietal branches.
- Visceral branches.
At the level of the IV–V lumbar vertebra, the aortic bifurcation occurs—the division of the main trunk into two aa. iliacae communes (common iliac arteries). The latter diverge at an angle of 30–60°, have a length of 5–7 cm, and divide into internal and external branches at the level of the sacroiliac joint.
Anatomy and course of the inferior vena cava
Vena cava inferior is formed retroperitoneally at the level of the IV–V lumbar vertebrae by the confluence of the common iliac veins. From its origin, the venous trunk ascends to the right of the vertebral column, after which it deviates anteriorly and to the right toward the caval opening of the diaphragm.
During its course, the vein interacts closely with the hepatic parenchyma, lying in a special notch on its posterior border where it is surrounded by liver tissue on three sides. In its lower parts, the venous trunk is crossed anteriorly by the right common iliac artery, the right testicular (or ovarian) artery, and the roots of the mesentery of the small intestine and transverse colon.
Tributary system and azygous vein
Blood drains into the inferior vena cava via parietal and visceral tributaries. A specific feature of the venous drainage of the retroperitoneal space is also the presence of the azygous vein (v. azygos) and hemiazygous vein (v. hemiazygos), which ascend along the anterolateral surfaces of the lumbar vertebral bodies.
These veins are the direct continuation of the vv. lumbales ascendentes (ascending lumbar veins) and are formed from vertical venous anastomoses of the lumbar veins, after which they pierce the diaphragm into the thoracic cavity.
Briefly: answers to topical questions
What unpaired visceral branches arise from the abdominal aorta?
Three unpaired visceral branches arise from the abdominal aorta.
- Celiac trunk (truncus coeliacus)—arises immediately below the diaphragm at the level of TXII.
- Superior mesenteric artery (a. mesenterica superior)—arises at the level of LI.
- Inferior mesenteric artery (a. mesenterica inferior)—arises from the lower third of the aorta at the level of LIII.
What paired visceral branches arise from the abdominal aorta?
The following paired visceral branches arise from the abdominal aorta:
- Middle suprarenal arteries (aa. suprarenales mediae)—thin branches running to the suprarenal gland hilum.
- Renal arteries (aa. renales)—large vessels branching off at the level of L1–L2.
- Gonadal arteries—testicular arteries (aa. testiculares) in males and ovarian arteries (aa. ovaricae) in females, branching off inferior to the renal arteries.
What parietal branches arise from the abdominal aorta?
Paired and unpaired parietal branches arise from the abdominal aorta.
- Inferior phrenic arteries (aa. phrenicae inferiores)—paired, directed toward the abdominal surface of the diaphragm.
- Lumbar arteries (aa. lumbales)—4 pairs, arising from the posterior surface of the aorta.
- Median sacral artery (a. sacralis mediana)—an unpaired thin vessel originating at the aortic bifurcation at the level of L5.
What visceral tributaries drain into the inferior vena cava?
The following visceral tributaries drain into the inferior vena cava:
- Hepatic veins (vv. hepaticae)—drain directly before the vein passes through the diaphragm.
- Renal veins (vv. renales)—form in the renal hilum and drain at a right angle.
- Suprarenal veins (vv. suprarenales)—the right one drains into the inferior vena cava.
- Testicular / ovarian veins (vv. testiculares / ovaricae)—the right one drains into the inferior vena cava.
What parietal tributaries drain into the inferior vena cava?
Parietal tributaries of the inferior vena cava include:
- Lumbar veins (vv. lumbales)—4 on each side, running along the intercostal spaces and collecting blood from the abdominal walls.
- Inferior phrenic veins (vv. phrenicae inferiores)—paired vessels that collect blood from the inferior surface of the diaphragm.
What is the topographic feature of the termination of the left testicular (ovarian) vein compared to the right one?
The topographic feature lies in the different sites of termination of these veins depending on the side.
| Vein | Site of termination |
|---|---|
| Right testicular (ovarian) vein (v. testicularis/ovarica dextra) | Drains directly into the inferior vena cava |
| Left testicular (ovarian) vein (v. testicularis/ovarica sinistra) | Drains into the left renal vein |
The aorta runs on the left and is covered by the pancreas and duodenum, whereas the inferior vena cava runs on the right and is situated behind the liver.
Class and exam questions
Where does the abdominal aorta begin and end?
It originates from the aortic hiatus of the diaphragm and terminates at the level of the IV–V lumbar vertebrae by its bifurcation.
How is the inferior vena cava positioned relative to the aorta?
The inferior vena cava is located to the right of the aorta, and the left wall of the vein itself lies directly adjacent to the aortic trunk.
Where is the inferior vena cava formed?
It is formed retroperitoneally at the level of the IV–V lumbar vertebrae by the union of the right and left common iliac veins.
What else to study on this topic
- Classification of visceral and parietal branches of the abdominal aorta
- Detailed syntopy of the inferior vena cava at the liver level
- Topography of the lumbar lymph nodes
- Anatomical features of the course of the azygos and hemiazygos veins
- Syntopy of the common iliac vessels
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