Medulla in general means the inner part, and derives from the Latin word for 'marrow'. In medicine it is contrasted to the cortex. Examples of its use include: 1  the medulla oblongata, a part of the brain stem. 2  the renal medulla, a part of the kidney. 3  the adrenal medulla, a part of the adrenal gland. 4  medulla spinalis, another term for spinal cord.