Overview
This lecture covers the anatomy of the spleen, including its location, external features, relations, blood supply, and clinical significance.
Introduction and Location
- The spleen is a lymphatic organ connected to the circulatory system, filtering old red blood cells from the blood.
- Located mainly in the left hypochondriac region and partly in the epigastric region of the abdomen.
- Positioned obliquely, directed downward, forward, and laterally, reaching the mid-axillary line.
Dimensions and Position
- Thickness: 1 inch; Breadth: 3 inches; Length: 5 inches.
- Weight: 7 ounces.
- Related to the 9th, 10th, and 11th ribs.
- Wedge-shaped between the fundus of the stomach (anterior) and diaphragm (posterior).
External Features
- Two ends: anterior (border-like, lateral, expanded) and posterior (rounded, medial).
- Three borders: superior (sharp, may have notches), inferior (rounded), intermediate (rounded, inner side).
- Two surfaces: diaphragmatic (smooth, convex), visceral (concave, irregular).
- Two angles: anterobasal (near anterior end, clinical angle), posterobasal (between inferior border and anterior end).
- One hilum where vessels and nerves enter.
Peritoneal and Visceral Relations
- Peritoneal ligaments:
- Gastrosplenic (hilum to stomach, contains short gastric vessels).
- Lienorenal (hilum to left kidney, contains tail of pancreas and splenic vessels).
- Phrenicocolic (supports anterior end, diaphragm to colon).
- Visceral impressions:
- Gastric (fundus of stomach, most concave).
- Renal (anterior surface of left kidney).
- Colic (splenic flexure of colon).
- Pancreatic (tail of pancreas).
Anatomical Position and Blood Supply
- Place spleen in left hand, directed obliquely at 45° with gastric impression superior.
- Blood supply: splenic artery (from celiac trunk), enters at hilum.
- Venous drainage: splenic vein joins superior mesenteric vein to form portal vein.
Clinical Significance (Applied Anatomy)
- Spleen not palpable unless enlarged (splenomegaly, e.g., malaria, leukemia).
- Splenectomy may be needed; avoid injuring tail of pancreas and splenic ligaments.
- Splenic puncture: needle inserted between 9th and 10th ribs at left mid-axillary line for diagnostic purposes.
- Splenic infarct: blockage of splenic artery branch causes necrosis, leads to pain referred to left shoulder (Cave’s sign).
- Spleen prone to rupture from trauma to left upper abdomen.
Key Terms & Definitions
- Hilum — region where vessels and nerves enter or exit an organ.
- Splenomegaly — enlargement of the spleen.
- Splenectomy — surgical removal of the spleen.
- Splenic infarct — tissue death in the spleen due to blood supply blockage.
- Gastrosplenic ligament — peritoneal fold connecting spleen hilum to stomach.
- Lienorenal ligament — peritoneal fold connecting spleen to left kidney.
- Cave’s sign — left shoulder pain from splenic infarct.
Action Items / Next Steps
- Review splenic anatomy and related peritoneal ligaments.
- Memorize spleen dimensions and positions.
- Prepare for questions on clinical situations involving spleen (e.g., splenomegaly, splenectomy, infarct).