19.Spleen

• Spleen


  • Large vascular organ
  • Lying against the diaphragm and 9th to 11th ribs in the left hypochondriac region
  • Covered with peritoneum EXCEPT at the hilum
  • MESODERMAL in origin
  • Composed of WHITE PULP which consists primarily lymphatic tissue (site of immune and phagocytic action) and RED PULP which consists of venous sinusoids and splenic cords (primary site of Filtration)
  • Occupies the left upper part of the abdomen between stomach and diaphragm
  • Oval shaped; notched anterior border
  • Weighs around 150 gms and about 5 inches long, 3 inches wide and 1.5 inches thick
• Spleen


  • Relations: Anteriorly - Stomach; tail of pancreas, left colic flexure
  • Medial border - L Kidney
  • Posteriorly - Diaphragm, Left pleura, Left lung, 9th, 10th and 11th ribs
• Gastrosplenic omentum/ligament


  • Between the hilum and greater curvature of stomach
  • Carries the Short Gastric and Left Gastroepiploic vessels
• Splenicorenal ligament


  • Between spleen and left kidney
  • Carries the Splenic vessels
• Blood supply to the spleen

  Splenic artery along the upper border of the pancreas
• Venous drainage


  1. Splenic vein runs behind the tail and body of the pancreas

  2. Splenic vein joins the Superior mesenteric vein

  3. Superior mesenteric vein forms the Portal vein
• Nerve supply


  Celiac plexus
• Psoas Major


  • Thick, fusiform
  • "muscle of the loin"
• Iliacus


  • Large, triangular on the lateral side of Psoas major
• Quadratus Lumborum


  • Quadrilateral
• Lumbar plexus


  1. Formed within the Psoas major muscle

  2. By the ventral rami of L1 - L4

  3. Branches emerge from the lateral and medial borders and from its anterior surface
• Iliohypogastric


  • Branch from L1
  • Emerges from the lateral border of Psoas
  • Runs in front of Quadratus lumborum
  • Supplies the skin of the lower part of the anterior abdominal wall
• Ilioinguinal


  • Branch from L1
  • Emerges from the lateral border of Psoas
  • Runs in front of Quadratus lumborum
  • Passes through the Inguinal canal to supply the skin of the groin and the scrotum / labia majora
• Genitofemoral


  • Branch from L1 and L2
  • Emerges from the anterior surface of Psoas
  • Divides into:
  • Genital branch - cremaster muscle
  • Femoral branch - skin on thigh
• Cremasteric reflex
• Lateral femoral cutaneous


  • Branch from L2 & L3
  • Emerges from the lateral border of Psoas
  • Crosses the Iliacus and enters the thigh behind the Inguinal ligament
  • Supplies the skin over the lateral surface of the thigh
• Lumbo-sacral plexus


  Lies on the posterior pelvic wall in front of the Piriformis muscle, formed by the anterior rami of L4 and L5 and S1 – S4
• Branches of the lumbo-sacral plexus

  1. To the Lower limb that leave the Pelvis through the Greater Sciatic foramen

  2. To the Pelvic muscles, Pelvic viscera and Perineum
• Branches to the Lower limb

  • Sciatic (L4, L5, S1, S2 and S3)
  • Superior Gluteal (L4, L5 and S1) – Gluteus medius/minimus
  • Inferior Gluteal – (L5, S1 and S2) Gluteus maximus
  • Nerve to Quadratus femoris
  • Nerve to Obturator internus
  • Posterior cutaneous nerve of the thigh
• Branches to the Pelvic muscles, Pelvic viscera and Perineum

  • Pudendal (S2, S3 and S4) - perineum
  • Nerve to Piriformis
  • Pelvic Splanchnic nerves (S2, S3 and S4)
• Perforating cutaneous nerve


  Supplies the skin on the lower medial part of the buttock