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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.

See Medullary.

Pertaining to, consisting of, or resembling, marrow or medulla.

Furnished with a medulla or marrow, or with a medullary sheath; as, a medullated nerve fiber.

Not medullated; (Anat.) without a medulla or marrow, or without a medullary sheath; as, a nonmedullated nerve fiber.

a hair, the "root," or part whence the hair originates. -- Bulb of the spinal cord, the medulla oblongata, often called simply bulb. -- Bulb of a tooth, the vascular and nervous papilla contained in the cavity of the tooth.

ertaining to bulb; especially, in medicine, pertaining to the bulb of the spinal cord, or medulla oblongata; as, bulbar paralysis.

The large lobe of the hind brain in front of and above the medulla; the little brain. It controls combined muscular action. See Brain.

o it; crura cerebri, two bundles of nerve fibers in the base of the brain, connecting the medulla and the forebrain.

The layer of vascular connective tissue lining the medullary cavities of bone.

grain of timber which is transverse to the annular rings or plates; the direction of the medullary rays in oak and some other timber. Knight.

The tissue which fills the cavities of most bones; the medulla. In the larger cavities it is commonly very fatty, but in the smaller cavities it is much less fatty, and red or reddish in color.

A variety of lignin or cellulose found in the medulla, or pith, of certain plants. Cf. Lignin, and Cellulose.

The posterior part of the brain, including the medulla; the afterbrain. Sometimes abbreviated to meten.

A soft white substance constituting the medullary sheats of nerve fibers, and composed mainly of cholesterin, lecithin, cerebrin, albumin, and some fat.

ithelium cells, and resembling, if not identical with, the substance (myelin) forming the medullary sheaths of nerve fibers.

rve fiber (Anat.), one of the fibers of which nerves are made up. These fibers are either medullated or nonmedullated. in both kinds the essential part is the translucent threadlike axis cylinder which is continuous the whole length of the fiber. -- Nerve stretching (Med.), the operation of stretching a nerve in order…

e enteron; as, the neurenteric canal, which, in embroys of many vertebrates, connects the medullary tube and the primitive intestine. See Illust. of Ectoderm.

ce, resembling keratin, present in nerve tissue, as in the sheath of the axis cylinder of medullated nerve fibers. Like keratin it resists the action of most chemical agents, and by decomposition with sulphuric acid yields leucin and tyrosin.

An elastic cartilagelike rod which is developed beneath the medullary groove in the vertebrate embryo, and constitutes the primitive axial skeleton around which the centra of the vertebræ and the posterior part of the base of the skull are developed; the chorda dorsalis. See Illust. of Ectoderm.