High-yield summary

Concise surgical anatomy of the abdomen focused on peritoneal coverings, regional landmarks, inguinal anatomy, major vascular supplies, and key retroperitoneal organs.

Peritoneal coverings — definitions

• Intraperitoneal: organ suspended by a mesentery and almost completely covered by visceral peritoneum; mobile (e.g., transverse colon, sigmoid, spleen).
• Retroperitoneal: lies posterior to the peritoneum; only anterior surface covered (e.g., kidneys, pancreas except tail).
• Mesoperitoneal (secondarily retroperitoneal): started intraperitoneal in development then fused to posterior abdominal wall (e.g., ascending and descending colon).
• Extraperitoneal: outside the peritoneal cavity (usually pelvic structures, lower rectum).

Organ coverings (quick reference)

Core anatomical concepts to memorize

• Stratigraphy: layered relationships (skin → fascia → muscle → fascia → peritoneum).
• Syntopy: relations between organs (what touches what).
• Holotopy: organ position relative to body as a whole.
• Skeletotopy: relation of organs to skeletal landmarks.

Abdominal regions (9) — what to know

• Nine-region grid: Right/Left Hypochondriac, Epigastric, Right/Left Lumbar (flank), Umbilical, Right/Left Iliac (inguinal), Hypogastric (suprapubic).
• Focus clinically on epigastric, hypochondriac, and inguinal regions for organ localization and exam.

Anterior abdominal wall & rectus sheath

• Arcuate line: key landmark.
• Above arcuate line: posterior rectus sheath present (aponeuroses of internal oblique + transversus abdominis form posterior sheath).
• Below arcuate line: posterior sheath absent; all aponeuroses pass anterior to rectus, leaving transversalis fascia posteriorly.
• Clinical relevance: below arcuate line is a weaker area—hernias more likely.

Inguinal canal — walls and contents

• Walls:
• Anterior: external oblique aponeurosis.
• Posterior: transversalis fascia.
• Roof (superior): internal oblique + transversus abdominis.
• Floor (inferior): inguinal ligament (Poupart's).
• Spermatic cord contents (important):
• Testicular (gonadal) artery, ductus deferens, pampiniform plexus of veins.
• Also: cremasteric vessels, nerves (ilioinguinal runs in canal wall), lymphatics.
• Scrotal layers (correspond to abdominal wall): skin → dartos fascia → external spermatic fascia → cremasteric fascia/muscle → internal spermatic fascia → tunica vaginalis (parietal) → tunica albuginea.

Hernias — quick rules

• Indirect inguinal hernia: through deep inguinal ring; lateral to inferior epigastric vessels; may enter scrotum; usually congenital (patent processus vaginalis).
• Direct inguinal hernia: through Hesselbach's triangle; medial to inferior epigastric vessels; rarely into scrotum; acquired (weakened wall).
• Remember location relative to inferior epigastric artery (a branch of the external iliac artery).

Peritoneal pouches

• Male: rectovesical pouch between rectum and bladder.
• Female: rectouterine pouch (Pouch of Douglas) — deepest point of peritoneal cavity when supine.

Portal triad & epiploic foramen (Winslow's foramen)

• Portal triad within hepatoduodenal ligament (at porta hepatis): from left → right: hepatic artery (left), portal vein (posterior/between), bile duct (right).
• Epiploic (Winslow's) foramen boundaries:
• Anterior: hepatoduodenal ligament (contains portal triad).
• Posterior: inferior vena cava.
• Superior: caudate lobe of liver.
• Inferior: first part of duodenum.

Stomach vascular supply (short summary)

• Lesser curvature: left gastric (from celiac trunk) and right gastric (from proper hepatic).
• Greater curvature: left gastroepiploic (from splenic) and right gastroepiploic (from gastroduodenal).
• Fundus: short gastric arteries (from splenic artery).

Porto–caval (portosystemic) anastomoses — clinical point

• Left gastric (portal) ↔ esophageal veins (systemic) at gastroesophageal junction — site of esophageal varices in portal hypertension.

Spleen — key facts

• Most mobile abdominal organ; protected by ribs IX–XI.
• Supplied by splenic artery; related to tail of pancreas.

Pancreas and duodenum

• Pancreas: retroperitoneal except tail which lies in lienorenal ligament and is intraperitoneal.
• Head blood supply from pancreaticoduodenal arteries (branches of gastroduodenal and superior mesenteric arteries).
• Body/tail blood supply from splenic artery branches.
• Duodenum: four parts; ligament (suspensory) of Treitz supports duodenojejunal flexure — important surgical landmark and differentiates upper vs lower GI bleeding.

Appendix & colon

• Appendix: McBurney's point = 1/3 the distance from ASIS to umbilicus (typical site of maximal tenderness).
• Appendicular artery: branch of the ileocolic artery (from SMA).
• Colon coverings:
• Ascending & descending colon: mesoperitoneal (secondarily retroperitoneal).
• Transverse & sigmoid colon: intraperitoneal with mesenteries.

Rectum — blood supply and levels

• Superior rectal artery — branch of inferior mesenteric artery (IMA).
• Middle rectal artery — branch of internal iliac artery.
• Inferior rectal artery — branch of internal pudendal artery.
• Clinical relevance: different lymphatic drainage and venous drainage routes.

Retroperitoneal contents (core list)

• Adrenal glands, kidneys, ureters, aorta, inferior vena cava, pancreas (except tail), duodenum (except proximal bulb).

Rapid mnemonics & exam tips

• Hernia location: remember relation to inferior epigastric vessels (indirect = lateral, direct = medial).
• Rectus sheath: ask “Is posterior sheath present?” — present above arcuate line, absent below.
• Portal triad order at porta hepatis: artery — vein — duct (artery left, duct right; vein posterior).
• Memorize the 9-region grid and where common organs sit (epigastrium for stomach/pancreas, right hypochondrium for liver/gallbladder, iliac/inguinal for appendix/ovaries).

Final one-line checklist (for quick revision)

• Peritoneal coverings; 9 regions; rectus sheath above/below arcuate line; inguinal canal walls; hernia locations; inferior epigastric origin; spermatic cord contents; scrotal layers; peritoneal pouches; portal triad; Winslow foramen boundaries; stomach arteries; porto-caval anastomosis; spleen ribs; pancreas blood supply; duodenum parts + ligament of Treitz; appendix location + artery; colon coverings; rectal arteries; retroperitoneal organs.