Dictionary:

medulla

  (mĭ-dŭl'ə)

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1. The inner core of certain organs or body structures, such as the marrow of bone.
2. The medulla oblongata.
3. See myelin.
4. Botany.
   1. The pith in the stems or roots of certain plants.
   2. The central portion of a thallus in certain lichens and red or brown algae.

[Middle English, from Latin, perhaps alteration (influenced by medius, middle; see medial) of *merulla.]

1. The central part of an organ.

2. The myelin portion of some nerve fibres. Such a fibre is called medullated.

Pl. medullae [L.] the central or inner portion of an organ.

• adrenal m. — the inner portion of the adrenal gland, where epinephrine is produced.
• m. of bone — bone marrow, contained in the medullary canal of bone.
• m. oblongata — that part of the hindbrain continuous with the pons anteriorly and the spinal cord posteriorly; it houses nerve centers for both motor and sensory nerves, where such functions as breathing and the beating of the heart are controlled. Called also myelencephalon. In animals the principal clinical manifestations of local lesions in the medulla are those of head rotation and circling, and facial and tongue paralysis with resulting difficulty in prehension and swallowing. With diffuse lesions spastic paralysis or a stiff-legged incoordination occurs.
• m. ossium — bone marrow.
• renal m. — the inner part of the substance of the kidney, composed chiefly of collecting tubules, and in some species organized into a group of structures called the renal pyramids.
• spinal m., m. spinalis — spinal cord.
• m. of thymus — the central portion of each lobule of the thymus; it contains many more reticular cells and far fewer lymphocytes than does the surrounding cortex.

Pith; the soft tissue in the center of young shoots and roots.

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:

• the medulla oblongata, a part of the brain stem
• the renal medulla, a part of the kidney
• the adrenal medulla, a part of the adrenal gland
• medulla ossea, the marrow inside the bone
• medulla spinalis, another term for spinal cord
• Medulla of ovary

Other non-medical uses of the term include:

• Medúlla, a 2004 music album by Icelandic singer Björk.
• Medulla, Florida, a U.S. city
• Las Médulas, Ancient Roman gold mines in León, Spain, UNESCO World Heritage Site.
• Medula the Deviant, Marvel Comics character

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