Definition of: medulla

(mə·dul′ə) noun plural -lae (-ē)
1. Anat. a The inner portion of an organ or part, distinguished from the cortex. b The marrow of long bones. c The pith of a hair. d The spinal cord: also medulla spi·na·lis (spī·nā′lis).
2. The ganglion of the brain which, connecting with the spinal cord, controls breathing, swallowing, circulation, etc.: also medulla ob·lon·ga·ta (ob′lông·gä′tə).
3. Bot. The inner central columnar mass of parenchymatous tissue in the stems and roots of certain plants; also, in lichens, the middle layer of tissue composing the thallus, and in fungi proper, the central tissue within the rind of the fungus body. [<L <medius middle]
—med·ul·lar·y (med′ə·ler′ē, mi·dul′ər·ē), me·dul′lar adjective