Abdomen: Anatomy, Clinical Correlates, and Key Concepts Flashcards

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Peritoneum

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A serous membrane with parietal and visceral layers that lines the abdominal cavity and covers intraperitoneal organs. It forms mesenteries and ligaments, provides a route for vessels, nerves, and lymphatics, and creates potential spaces for fluid accumulation.

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Mesentery

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A double layer of peritoneum that suspends parts of the intestine from the posterior abdominal wall. It transmits blood vessels, nerves, and lymphatics to the attached organ and allows mobility while maintaining vascular supply.

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Celiac trunk

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The first major anterior branch of the abdominal aorta supplying foregut structures including the stomach, liver, spleen, and proximal duodenum. It typically branches into the left gastric, splenic, and common hepatic arteries.

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Superior mesenteric artery

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An aortic branch that supplies midgut derivatives from distal duodenum to the proximal two-thirds of the transverse colon. It provides important branches like intestinal arteries and the ileocolic, right colic, and middle colic arteries.

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Inferior mesenteric artery

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An aortic branch supplying hindgut structures from the distal one-third of the transverse colon to the upper rectum. Major branches include the left colic, sigmoid arteries, and the superior rectal artery.

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Hepatic portal vein

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A venous channel formed by the confluence of the splenic and superior mesenteric veins that carries nutrient-rich blood from the GI tract to the liver for processing. It is central to the portal venous system and portal hypertension pathophysiology.

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Liver segments

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Functional subdivisions of the liver based on portal vein and biliary distribution (Couinaud segments). Segmental anatomy guides surgical resections and hepatic procedures by correlating vascular inflow and outflow territories.

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Gallbladder

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A pear-shaped intraperitoneal organ that stores and concentrates bile, releasing it into the cystic duct and common bile duct during digestion. It lies on the visceral surface of the liver in the right upper quadrant.

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Pancreas

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An organ with both exocrine (digestive enzyme secretion) and endocrine (insulin, glucagon) functions. It is mostly retroperitoneal with head adjacent to the duodenum and tail reaching the spleen.

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Spleen

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An intraperitoneal organ involved in immune function and red blood cell turnover, located in the left upper quadrant beneath the rib cage. It is vascular and vulnerable to injury in blunt abdominal trauma.

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Appendix

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A narrow, blind-ended tubular structure arising from the cecum, often intraperitoneal and variable in position. Inflammation (appendicitis) typically produces migratory pain from periumbilical area to the right lower quadrant.

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Kidneys

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Retroperitoneal organs that filter blood to produce urine and regulate fluid and electrolyte balance. They receive arterial blood from the renal arteries and drain via the renal veins into the IVC.

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Adrenal glands

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Endocrine organs located superior to the kidneys producing steroid hormones (cortex) and catecholamines (medulla). Their arterial supply is rich, typically from three sources, and venous drainage is asymmetric (right to IVC, left to left renal vein).

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Inguinal canal

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An oblique passage through the lower anterior abdominal wall transmitting the spermatic cord in males and the round ligament in females. Its anatomy is clinically important for understanding direct and indirect inguinal hernias.

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Rectus sheath

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A fibrous compartment formed by the aponeuroses of the lateral abdominal muscles that encloses the rectus abdominis. The composition of the sheath changes below the arcuate line, affecting surgical and clinical considerations.

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Arcuate line

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A horizontal anatomical landmark on the posterior rectus sheath marking where the posterior layer ends and the transversalis fascia is exposed. Below this line the rectus abdominis is covered anteriorly only, altering structural support.

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Ascites

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Pathological accumulation of fluid in the peritoneal cavity often secondary to portal hypertension, malignancy, or infection. Clinically it presents with abdominal distension, shifting dullness, and can impair respiration when severe.

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Peritonitis

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Inflammation of the peritoneum caused by infection, chemical irritation, or rupture of viscera, producing abdominal pain, guarding, and rebound tenderness. It is a surgical emergency when due to perforation or widespread infection.

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Morrison's pouch

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The hepatorenal recess between the liver and right kidney; the most dependent subhepatic space in supine patients. It is a common site for fluid collection and is assessed on ultrasound in trauma evaluations.

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Round ligament of liver

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A fibrous remnant of the fetal umbilical vein (ligamentum teres hepatis) within the free edge of the falciform ligament connecting the liver to the anterior abdominal wall. It is an important surface landmark in abdominal imaging and surgery.