Lymphatic Anatomy


Lymphatic Anatomy, Lymphatic System, Lymphatic Circulation, Lymphatics, Lymph Node, Lymph, Chyle, Lymphoid Tissue, Thoracic Duct

  • Definitions
  1. Lymph
    1. Clear to yellow translucent fluid containing primarily Lymphocytes
    2. Flows from peripheral tissues via lymphatic vessels and Lymph Nodes
    3. Lymph re-enters venous system via the Thoracic Duct at the left subclavian
  2. Chyle
    1. Opaque, milky fluid containing both lymph and emulsified fats
    2. Absorbed at the lacteals within the Small Intestines
    3. Flows from the intestinal tract into the Lymphatic System
  3. Lymphoid Tissue
    1. Tissue within the Lymphatic System in which Lymphocytes form, mature and multiply
    2. Lymphoid Tissue is interconnected via lymphatic vessels
  4. Lymph Node
    1. Rounded, bean-shaped collection of lymphatic tissue contained within a connective tissue capsule
    2. The adult human body contains roughly 500 Lymph Nodes, normally <2 cm each
  5. Thoracic Duct
    1. Largest of the lymphatic vessels, draining directly into the left subclavian vein
    2. Central lymphatic drain that collects flow from the tree network of Lymphatics throughout the body
  • Physiology
  • Lymph Node
  1. Lymph Nodes store Lymphocytes within Nodules (lobules)
    1. Lymph Node Outer Cortex (Germinal Tissue, Follicle)
      1. Contains Inactive B Cells ready to respond to Antigens
    2. Lymph Node Inner Paracortex
      1. Contains T Helper Cells and Dendritic Cells
  2. Lymph Nodes contain a mesh framework that filters lymph fluid of Antigens
    1. B Lymphocytes within Lymph Node germinal centers are stimulated to divide by specific Antigens
    2. Specifically responding B Lymphocytes divide into Antibody producing plasma cells and memory cells
  3. Lymph Nodes are supplied by Lymphatics and a vascular tree
    1. Afferent Lymphatics pass through the Lymph Node capsule and into each Nodule
    2. Lymph flows from the outer cortex (B Cells) to the inner cortex (T Helper Cells) to the Medullary region
    3. Lymph Node central Medullary region collects all flow from the lymph Nodules
      1. Efferent Lymphatics exit the Medullary region and flow to the next Lymph Node
      2. Medullary region also contains arteries and veins