Overview of Neurovascular Structures

2 Overview of Neurovascular Structures


2.1 Branches of the Abdominal Aorta: Overview and Paired Branches



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A Overview of the abdominal aorta and pelvic arteries (abdominal organs removed)


Anterior view (female pelvis). The esophagus has been pulled slightly inferiorly, and the peritoneum has been completely removed. The abdominal aorta is the distal continuation of the thoracic aorta. It descends slightly to the left of the midline to approximately the level of the L 4 vertebra, as shown in B (or possibly to the L 5 vertebra in older individuals). There it divides into the paired common iliac arteries (aortic bifurcation). The common iliac arteries divide further into the internal and external iliac arteries. The abdominal aorta (see C) and its major branches give origin to various “subbranches” that supply the abdomen and pelvis (see D).




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C Sequence of branches from the abdominal aorta


D Functional groups of arteries that supply the abdomen and pelvis


The branches of the abdominal aorta and pelvic arteries can be divided into five broad functional groups (→ = give rise to). For details about the areas supplied by the unpaired branches see p. 213.


























Paired branches (and one unpaired branch) that supply the diaphragm, kidneys, suprarenal glands, posterior abdominal wall, spinal cord, and gonads (see C)


Right and left inferior phrenic arteries


Right and left superior suprarenal arteries


Right and left middle suprarenal arteries


Right and left renal arteries


Right and left inferior suprarenal arteries


Right and left testicular (ovarian) arteries


Right and left lumbar arteries (first through fourth)


Median sacral artery (with lowest lumbar arteries)


One unpaired trunk that supplies the liver, gallbladder, pancreas, spleen, stomach, and duodenum (see C, pp. 213 and 265)


Celiac trunk with


Left gastric artery


Splenic artery


Common hepatic artery


One unpaired trunk that supplies the small intestine and large intestine as far as the left colic flexure (see C, pp. 213 and 269)


Superior mesenteric artery


One unpaired trunk that supplies the large intestine from the left colic flexure (see C, p. 213)


Inferior mesenteric artery


One indirect (see below) paired trunk that supplies the pelvis (see A, p. 213)


Internal iliac artery (from the common iliac artery, not directly from the aorta, hence an “indirect paired trunk”)


2.2 Branches of the Abdominal Aorta: Unpaired and Indirect Paired Branches



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A Classification of arteries supplying the abdomen and pelvis


Red: Branches of the celiac trunk. These supply the proximal bowel segments from the abdominal esophagus to the pancreas and duodenum.


Green: Branches of the superior mesenteric artery. These supply the middle bowel segments from the pancreas and duodenum to the left colic flexure.


Blue: Branches of the inferior mesenteric artery. These supply the distal bowel segments from the left colic flexure to the rectum.




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C Abdominal arterial anastomoses


1 Between the celiac trunk and superior mesenteric artery via the pancreaticoduodenal arteries


2 Between the superior and inferior mesenteric arteries (middle and left colic arteries; Riolan and Drummond anastomoses, see A)


3 Between the inferior mesenteric artery and internal iliac artery (superior rectal artery and middle or inferior rectal artery)


These anastomoses are important in that they can function as collaterals, delivering blood to intestinal areas that have been deprived of their normal blood supply.


D Classification of the arteries supplying the abdomen and pelvis


For the area supplied by the paired branches see p. 211 (→ = is continuous with).


Note the anastomoses particularly between the unpaired trunks (see Fig. A and C).








































One unpaired trunk that supplies the liver, gallbladder, pancreas, spleen, stomach, and duodenum (see A)


Celiac trunk with


Splenic artery


Left gastro-omental artery


Posterior gastric artery (and short gastric arteries)


Pancreatic branches


Caudal pancreatic artery


Great pancreatic artery


Dorsal pancreatic artery


Inferior pancreatic artery


Transverse pancreatic artery


Left gastric artery


Esophageal branches


Common hepatic artery


Gastroduodenal artery


Supraduodenal artery (inconstant branch of the gastroduodenal artery)


Retroduodenal artery


Right gastro-omental artery


Anterior or posterior superior pancreaticoduodenal artery


Duodenal branches


Right gastric artery


Proper hepatic artery


Cystic artery


One unpaired trunk that supplies the small intestine and large intestine as far as the left colic flexure (see A)


Superior mesenteric


Inferior pancreaticoduodenal artery artery


Jejunal and Ileal arteries


Ileocolic artery


Right colic artery


Middle colic artery


One unpaired trunk that supplies the large intestine from the left colic flexure (see A)


Inferior mesenteric artery


Left colic artery


Sigmoid arteries


Superior rectal artery


One indirect (see below) paired trunk that supplies the pelvis (see B)


Internal iliac artery (from the common iliac artery, not directly from the aorta, hence an “indirect paired trunk”) with branches that supply


 


Umbilical artery


Superior vesical artery


Artery of ductus deferens ♂


Inferior vesical artery


Uterine artery


Middle rectal artery


Internal pudendal artery


The pelvic walls (parietal branches)


 


Iliolumbar artery


Lateral sacral artery


Obturator artery


Superior and inferior gluteal arteries


2.3 Inferior Vena Caval System




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B Tributaries of the inferior vena cava


The difference in the venous drainage of the right and left kidneys is displayed more clearly here than in A. The continuity of the right ascending lumbar vein with the azygos vein is also shown.


Direct tributaries return venous blood directly to the inferior vena cava without passing through an intervening capillary bed. Direct tributaries drain the following organs:


The diaphragm, abdominal wall, kidneys, suprarenal glands, testes/ovaries, and liver


For the pelvis (via the common iliac vein) from the pelvic wall and floor, uterus, uterine tubes, bladder, ureters, accessory sex glands, lower rectum, and lower limb.


Indirect tributaries return blood that has passed through the capillary bed of the liver via the hepatic portal system (see p. 217). The following organs have indirect tributaries:


The spleen


The organs of the digestive tract: pancreas, duodenum, jejunum, ileum, cecum, colon, and upper rectum


Note: Venous blood from the inferior vena cava may drain through the ascending lumbar veins into the azygos or hemiazygos vein and thence to the superior vena cava. Thus a connection between the two venae cavae exists on the posterior wall of the abdomen and thorax: a cavocaval or intercaval anastomosis. The location and significance of cavocaval anastomoses are discussed on p. 218. Frequently an anastomosis exists between the suprarenal vein and inferior phrenic vein (not shown here, see A) on the left side of the body.



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C Projection of the inferior vena cava onto the vertebral column


The inferior vena cava ascends on the right side of the abdominal aorta and pierces the diaphragm at the caval opening located at the T 8 level. The common iliac veins unite at the L 5 level to form the inferior vena cava (see also A).


D Direct tributaries of the inferior vena cava



Right and left inferior phrenic veins


Hepatic veins


Right suprarenal vein


Right and left renal veins at the L 1/L 2 level (the left testicular/ovarian vein and left suprarenal vein terminate in the left renal vein)


Lumbar veins


Right testicular/ovarian vein


Common iliac veins (L 5 level)


Median sacral vein (often terminates in the left common iliac vein)


2.4 Portal Venous System (Hepatic Portal Vein)



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A The portal venous system in the abdomen


The arterial blood supply and venous drainage of the abdominal and pelvic organs differ in their functional organization: While they derive their arterial blood supply entirely from the abdominal aorta or one of its major branches, venous drainage is accomplished by one of two different venous systems:


1. Organ veins that drain directly or indirectly (via the iliac veins) into the inferior vena cava, which then returns the blood to the right heart (see also p. 214);


2. Organ veins that first drain directly or indirectly (via the mesenteric veins or splenic vein) into the portal vein—and thus to the liver—before the blood enters the inferior vena cava and returns to the right heart.


The first pathway serves the urinary organs, suprarenal glands, genital organs, and the walls of the abdomen and pelvis. The second pathway serves the organs of the digestive system (hollow organs of the gastrointestinal tract, pancreas, gallbladder) and the spleen (see D). Only the lower portions of the rectum are exempt from this pathway and drain directly through the iliac veins to the inferior vena cava. This (re)routing of venous blood through the hepatic portal system ensures that the organs of the digestive tract deliver their nutrient-rich blood to the liver for metabolic processing before it is returned to the heart. It also provides a route by which elements of degenerated red blood cells can be conveyed from the spleen to the liver. Thus, the portal vein functions to deliver blood to the liver to support metabolism. This contrasts with the proper hepatic artery, which supplies the liver with oxygen and other nutrients. Anastomoses may develop between the portal venous system and vena caval system (portacaval anastomosis) and function as collateral pathways in certain diseases (see p. 218).

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Aug 4, 2021 | Posted by in GENERAL SURGERY | Comments Off on Overview of Neurovascular Structures
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