Stomach and Intestines

Stomach and Intestines

Stomach and Intestines

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Stomach - The Acidic Mixer

Stomach Arterial Supply

  • Parts: Cardia, Fundus, Body, Pylorus (Antrum, Canal). J-shaped.
  • Curvatures: Lesser (R. gastric a.), Greater (R & L gastro-omental a.). Incisura angularis on lesser.
  • Relations (Posterior - Stomach Bed): Pancreas, spleen, L kidney, L suprarenal, transverse mesocolon, splenic a., diaphragm.
  • Arterial Supply (Celiac Trunk branches): L&R Gastric, L&R Gastro-omental, Short Gastrics.
  • Venous Drainage: Parallels arteries; drains to Portal system.
  • Lymphatics: Follow arteries to celiac, gastric, gastro-omental nodes.
  • Innervation:
    • Parasympathetic: Vagus (Ant/Post trunks of Latarjet) - ↑motility, ↑secretion.
    • Sympathetic: Greater Splanchnic n. (T6-T9) via celiac plexus - ↓motility, vasoconstriction.
  • Key Cells:
    • Parietal (oxyntic): HCl, Intrinsic Factor (for Vit B12 absorption).
    • Chief (peptic): Pepsinogen.
    • G-cells (antrum): Gastrin.

⭐ Posterior gastric ulcers may erode the splenic artery, causing major hemorrhage (commonest artery involved).

Small Intestine - Absorption Ace

  • Segments (Proximal to Distal): 📌 "Dow Jones Industrials"
    • Duodenum: ~25 cm; C-shaped; Brunner's glands (alkaline mucus); major iron absorption.
    • Jejunum: ~2.5 m; feathery appearance (prominent plicae circulares & villi); main site for nutrient absorption (carbs, fats, proteins, Ca).
    • Ileum: ~3.5 m; Peyer's patches (lymphoid aggregates); absorbs Vitamin B12 & bile salts.
  • Vascular Supply: Superior Mesenteric Artery (SMA) branches.
  • Absorption: Vast surface area via plicae circulares, villi, and microvilli.

    ⭐ The terminal ileum is the principal site for Vitamin B12 and bile acid reabsorption. Small Intestine Segments: Duodenum, Jejunum, Ileum A

Large Intestine - Water Warden

Anatomy of the Large Intestine and Associated Structures

  • Parts: Cecum & appendix, Colon (ascending, transverse, descending, sigmoid), Rectum, Anal canal.
  • Key Features:
    • Taeniae coli: Three longitudinal muscle bands.
    • Haustra: Sacculations of the colon wall.
    • Appendices epiploicae: Small fatty projections.
  • Blood Supply:
    • Arteries: Superior Mesenteric Artery (SMA) branches (ileocolic, right colic, middle colic); Inferior Mesenteric Artery (IMA) branches (left colic, sigmoidal, superior rectal).
    • Marginal artery of Drummond: Anastomotic arcade.
  • Primary Function: Water & electrolyte absorption; formation & storage of feces.

McBurney's point: Located one-third of the distance from the anterior superior iliac spine (ASIS) to the umbilicus; tenderness here is a sign of acute appendicitis. 📌

Gut Development & Clinicals - Twists & Troubles

  • Gut Development:
    • Foregut: Esophagus to D2, liver, pancreas.
    • Midgut: D2 to prox 2/3 TC. Rotates 270° CCW (SMA axis).
    • Hindgut: Distal 1/3 TC to upper anal canal.
  • Clinical Issues:
    • Meckel's: True diverticulum. Rule of 2s (📌 2% pop, 2ft ICV, 2in long, 2 ectopic tissues).
    • Hirschsprung's: Aganglionosis (neural crest failure); rectosigmoid.
    • Volvulus: Bowel twist (sigmoid/cecum); obstruction/ischemia.
    • Intussusception: Telescoping bowel (ileocolic); currant jelly stool.

⭐ Meckel's diverticulum, the most common congenital GI anomaly, results from incomplete obliteration of the vitelline duct.

High‑Yield Points - ⚡ Biggest Takeaways

  • Stomach's rich arterial supply from celiac trunk branches.
  • Meckel's diverticulum: most common GI anomaly, follows Rule of 2s.
  • Second part of duodenum contains major duodenal papilla; SMA crosses third part.
  • Jejunum: prominent plicae circulares, long vasa recta. Ileum: Peyer's patches.
  • Large intestine: characterized by Teniae coli, haustra, omental appendices.
  • Ligament of Treitz suspends the duodenojejunal (DJ) flexure.
  • Griffith's point (splenic flexure) is a key watershed area for colonic ischemia.
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Practice Questions: Stomach and Intestines

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_____duodenal recess has the inferior mesenteric vein in its right free margin.

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_____duodenal recess has the inferior mesenteric vein in its right free margin.

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