Pancreas and Spleen

Pancreas and Spleen

Pancreas and Spleen

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Pancreas Anatomy - Gut's Sweetbread Secret

  • Location: Mostly retroperitoneal (tail is intraperitoneal); L1-L2 level, posterior to stomach.
  • Parts (Right to Left):
    • Head: In C-loop of duodenum. Uncinate process posterior to SMV/SMA. Common Bile Duct (CBD) passes through/posterior.
    • Neck: Overlies Superior Mesenteric Vein (SMV), Superior Mesenteric Artery (SMA), portal vein origin.
    • Body: Crosses aorta, left kidney; posterior to omental bursa.
    • Tail: Reaches splenic hilum (within splenorenal ligament).
  • Ducts: Main pancreatic duct (Wirsung) joins CBD at ampulla of Vater. Accessory duct (Santorini) variable.

Pancreas Anatomy Diagram, main and accessory pancreatic ducts, and key relations like duodenum, superior mesenteric vessels (SMV, SMA), portal vein, splenic vein, and common bile duct)

  • Key Relations:
    • Posterior: IVC, aorta, portal vein, splenic vein, bile duct, left kidney.
    • Anterior: Stomach, transverse mesocolon.
  • Arterial Supply:
    • Head/Uncinate: Superior & Inferior pancreaticoduodenal arteries (from celiac trunk & SMA branches).
    • Body/Tail: Splenic artery branches.
  • Venous Drainage: Via pancreatic veins to splenic vein, SMV, then portal vein.

⭐ Cancer of the head of pancreas commonly causes painless obstructive jaundice due to CBD compression.

Pancreas Histo & Embryo - Islet Islands & Budding Beginnings

Exocrine Pancreas: Acini (serous, zymogen granules), centroacinar cells. Ducts: intercalated → intralobular → interlobular → main.

Endocrine Pancreas (Islets of Langerhans): 📌 Mnemonic (B-I-G A-G-S): Beta cells (Insulin - central, Greatest); Alpha cells (Glucagon); Delta cells (Somatostatin).

Cell TypeHormoneLocation (Islet)Primary Function
Beta (β)InsulinCentral↓ Blood glucose
Alpha (α)GlucagonPeripheral↑ Blood glucose
Delta (δ)SomatostatinInterspersedInhibits insulin/glucagon
PP (F/γ)Pancreatic PolypeptidePeripheral (head)Inhibits exocrine secretion

Embryology (Foregut Origin):

  • Dorsal bud → body, tail, superior head, accessory duct.
  • Ventral bud → inferior head, uncinate, main duct.
  • Rotation & fusion: Ventral bud rotates dorsally, fuses with dorsal; ducts fuse.

Congenital Anomalies:

  • Annular pancreas: duodenal obstruction.
  • Pancreas divisum: duct fusion failure.
  • Ectopic pancreas: atypical sites.

⭐ Pancreas divisum: failed dorsal/ventral duct fusion. Most common anomaly (~10%), risks pancreatitis.

Spleen Anatomy & Relations - Body's Blood Bank

  • Location: LUQ, intraperitoneal. Lies under left ribs 9-11, axis along 10th rib.
  • Normal Size/Weight: 📌 1x3x5 inches (thick x broad x long), 7oz (~200g).
  • Surfaces & Impressions:
    • Diaphragmatic: Convex, smooth; faces diaphragm.
    • Visceral: Concave; gastric, renal (L. kidney), colic (splenic flexure), pancreatic (tail) impressions.
  • Borders: Superior (notched), inferior, anterior (sharp), posterior.
  • Hilum: Medial aspect; entry/exit for splenic artery/vein, nerves.
  • Key Ligaments:
    LigamentContents
    GastrosplenicShort gastric, L. gastroepiploic vessels
    SplenorenalSplenic vessels, Pancreas tail
    PhrenicocolicSupports spleen inferiorly
  • Arterial Supply: Splenic artery (from celiac trunk) to hilum.
  • Venous Drainage: Splenic vein joins SMV to form Portal Vein.

Spleen anatomy: surfaces, impressions, ligaments

⭐ Tail of pancreas in splenorenal ligament: risk during splenectomy.

Spleen Histo & Functions - Red & White Sentinel

Histology: Fibroelastic capsule (smooth muscle), trabeculae. Spleen histology: red pulp, white pulp, and structures

Pulp TypeKey StructuresMain CellsPrimary Function(s)
Red PulpSplenic cords (Billroth), splenic sinusoidsMacrophages, RBCsFilters old RBCs/platelets; iron recycling
White PulpPALS, Follicles, Marginal zoneT-cells (PALS), B-cells (Follicles), MacrophagesImmune surveillance, antigen presentation, immune response
  • Blood via central arteries (white pulp).
  • Open theory: Arterioles to red pulp cords → sinusoids.
  • Closed theory: Arterioles direct to sinusoids. (Both occur).

Key Functions:

  • Immune: Activates lymphocytes, antibody production.
  • Filtration: Removes old RBCs/platelets, microbes.
  • Hematopoiesis: (Fetal).
  • Storage: RBCs, platelets.

⭐ Post-splenectomy: ↑ risk of overwhelming sepsis from encapsulated bacteria (e.g., Streptococcus pneumoniae, Haemophilus influenzae type b, Neisseria meningitidis) due to loss of splenic phagocytic and immune functions.

High‑Yield Points - ⚡ Biggest Takeaways

  • Pancreas: mostly retroperitoneal; tail is intraperitoneal in splenorenal ligament.
  • Head of pancreas in duodenal C-loop; uncinate process posterior to SMV/SMA.
  • Main pancreatic duct (Wirsung) joins CBD forming ampulla of Vater.
  • Spleen: intraperitoneal, related to left ribs 9-11.
  • Splenic artery (celiac trunk); splenic vein joins SMV forming portal vein.
  • Gastrosplenic ligament: short gastric vessels; Splenorenal ligament: splenic vessels, pancreatic tail.
  • Accessory spleens (splenunculi) are common, often near splenic hilum or tail of pancreas.

Practice Questions: Pancreas and Spleen

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Flashcards: Pancreas and Spleen

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The retroperitoneal structures of the GI tract may be remembered with the mnemonic "SAID PUCKER": S: _____AI: Aorta and IVC D: Duodenum (2nd through 4th part) P: Pancreas (except tail) U: Ureters C: Colon (ascending and descending) *surgeons consider these intraperitoneal K: KidneyE: Esophagus (thoracic portion) R: Rectum (partially)

TAP TO REVEAL ANSWER

The retroperitoneal structures of the GI tract may be remembered with the mnemonic "SAID PUCKER": S: _____AI: Aorta and IVC D: Duodenum (2nd through 4th part) P: Pancreas (except tail) U: Ureters C: Colon (ascending and descending) *surgeons consider these intraperitoneal K: KidneyE: Esophagus (thoracic portion) R: Rectum (partially)

Suprarenal (adrenal) glands

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