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1. A white fatty substance that forms a medullary sheath around the axis cylinder of some nerve fibers
   - myelin, myeline
    
2. Lower or hindmost part of the brain; continuous with spinal cord
   "the medulla oblongata is the most vital part of the brain because it contains centres controlling breathing and heart functioning";
   - medulla oblongata, bulb [archaic]
    
3. The inner part of an organ or structure in plant or animal

Derived forms: medullas, medullae

Type of: animal tissue, fat, neural structure, plant tissue

Antonym: cortex

Part of: brain stem, brainstem, brain-stem, medullary sheath, myelin sheath

Encyclopedia: Medulla, Florida