medulla

n. [ L. ] 1. Marrow; pith; hence, essence. [ Obs. ] Milton. [ 1913 Webster ]

2. (Anat.) The marrow of bones; the deep or inner portion of an organ or part; as, the medulla, or medullary substance, of the kidney; specifically, the medula oblongata. [ 1913 Webster ]

3. (Bot.) A soft tissue, occupying the center of the stem or branch of a plant; pith. [ 1913 Webster ]

4. See medulla oblongata. [ PJC ]

Medulla oblongata. [ L., oblong medulla ] (Anat.), the posterior part of the brain connected with the spinal cord. It includes all the hindbrain except the cerebellum and pons, and from it a large part of the cranial nerves arise. It controls very largely respiration, circulation, swallowing, and other functions, and is the most vital part of the brain; -- called also bulb of the spinal cord. See Brain. [ 1913 Webster ]