Overview
The retroperitoneum is an anatomical space located posterior to the peritoneal cavity where abdominal organs that are not suspended by the mesentery are bound between the transversalis fascia of the posterior abdominal wall (posteriorly) and posterior parietal peritoneum (anteriorly). The retroperitoneal space can be furthered divided into the anterior pararenal, posterior pararenal and perirenal spaces.
Spaces
Anterior Pararenal Space
Boundaries:
- Posterior parietal peritoneum anteriorly
- Anterior renal fascia (of Gerota) posteriorly
- Lateroconal fascia (continuation of posterior renal fascia) laterally
Contains:
- Head, neck and body of the pancreas (the tail of the pancreas lies within the splenorenal ligament)
- Ascending and descending large bowel
- Duodenum (except for D1 – proximal segment)
Perirenal space
The perirenal space has an inverted-cone shape, with the base resting on the diaphragm and apex pointing towards the pelvis. Its boundaries are:
- Anterior renal fascia (of Gerota) – blends anteriorly with connective tissue around the aorta and inferior vena cava
- Posterior renal fascia (of Zuckerkandl) – is thicker and composed of two lamina which blends with the quadratus lumborum fascia. The superficial lamina is made up of lateroconal fascia which extends anteriorly and attaches to peritoneum
Contains:
- Adrenal gland
- Kidneys
- Ureters
- Renal vessels
- Perirenal fat
Posterior Pararenal Space
Boundaries:
- Posterior renal fascia anteriorly
- Transversalis fascia posteriorly
Contains:
- No major organs
- Primarily pararenal fat, blood vessels and lymphatics
Great Vessel Compartment
- Laterally: perirenal space and ureter
- Posteriorly: vertebral body, psoas major muscle
- Superiorly: continuous with the posterior mediastinum
Contains:
- Abdominal aorta
- Inferior vena cava
- Fat
- Lymph nodes
Contents
SADPUCKER:
- Suprarenal (adrenal) glands
- Aorta/Inferior vena cava
- Duodenum (2nd and 3rd parts, i.e. except 1st part)
- Pancreas (head, uncinate process, body, i.e. except tail)
- Ureters
- Colon (ascending and descending, i.e. transverse)
- Kidneys
- Esophagus
- Rectum (except lower third)
Arterial Supply
- Provided by the abdominal aorta
Venous Drainage
- Drained by the inferior vena cava and its tributaries
Lymphatics
In general the retroperitoneal lymphatic chain follows blood vessels.
Within the abdomen:
- Inferior dipahragmatic nodes
- Lumbar nodes – surround the inferior vena cava and aorta and further classify as left lumbar, intermediate, and right lumbar.
- Aorta: pre-aortic, para-aortic, and retro-aortic nodes
- Inferior vena cava: pre-caval, para-caval, and retro-caval nodes
Within the pelvis:
- Common iliac, external and internal iliac nodes
- Obturator nodes
- Sacral lymph nodes.
Nerves
- Parietal nerves branch from the lumbar plexus bilaterally – iliohypogastric, ilioinguinal, genitofemoral, lateral femoral cutaneous, obturator, and femoral nerves.
- The lumbosacral trunk and ventral rami of S1-S3 and part of S4 come together to form the sacral plexus, which gives rise to many of the nerves found within the retroperitoneum.
- The superior and inferior gluteal nerves form from the sacral plexus bilaterally. Also arising from the sacral plexus are right and left lumbar sympathetic trunks, as well as the greater, lesser, and least thoracic splanchnic nerves and four lumbar splanchnic nerves. All of these provide sympathetic innervation to abdominal and pelvic viscera. The pelvic splanchnic nerves provide parasympathetic innervation to structures of the peritoneal cavity. The vagus and splanchnic nerves, along with coeliac, superior mesenteric, and aorticorenal ganglia form the autonomic plexuses. These carry sympathetic, parasympathetic, and sensory (predominantly pain) fibers
Muscles
- Posterior margin: transverse abdominal, psoas, quadratus lumborum, and iliacus
- Medial margin: paraspinous muscles on either side of the spine
- Lateral margin: abdominal musculature
- Superior margin: Partly by the diaphragm
- Inferior margin: Iliopsoas muscle
Development
Primary retroperitoneal structures are those that were retropertioneal during the entirety of development and includes the; adrenal glands, kidneys, ureters, abdominal aorta, inferior vena cava and anal canal.
Secondarily retropertioneal structures are those which were initially suspended in the mesentery, then later migrated posterior to the peritoneum during devlopment and includes the duodenum (except for D1 – proximal segment), ascending and descending large bowel and the pancreas (except the tail).