名詞 medulla:

1. a white fatty substance that forms a medullary sheath around the axis cylinder of some nerve fibers
   同義詞：myelin, myeline, medulla
2. lower or hindmost part of the brain; continuous with spinal cord; (`bulb' is an old term for medulla oblongata)
   同義詞：medulla oblongata, medulla, bulb
3. the inner part of an organ or structure in plant or animal
   同義詞：medulla