What is "medullae"

n. (en-irregular plural of: medulla)

n. (context obsolete English) (en-irregular plural of: medulla)

1. n. a white fatty substance that forms a medullary sheath around the axis cylinder of some nerve fibers [syn: myelin, myeline]

2. lower or hindmost part of the brain; continuous with spinal cord; (`bulb' is an old term for medulla oblongata); "the medulla oblongata is the most vital part of the brain because it contains centers controlling breathing and heart functioning" [syn: medulla oblongata, bulb]

3. the inner part of an organ or structure in plant or animal [ant: cortex]

4. [also: medullae (pl)]

See medulla