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[Latin] The pith of plants.

[Latin] Marrow (also called M. ossium).

[Latin] Any substance resembling marrow in its structure or position; any soft substance contained in bony canal; especially, the spinal cord (M. spinalis) and its prolongation in the brain (M. oblongata or simply M.). The m. oblongata lies at the base of the brain, and consist of the anterior pyramids, connecting the crossed and direct pyramidal tracts of the cord with the pyramidal (motor) tract of the brain; restiform bodies, which connect the cerebellar tracts of the cord with the cerebellum; gracile funiculus, which forms the continuation of the postero-median column of the cord, is expanded above into the clava (dorsal or posterior pyramid), and ends in the gracile nucleus; cuneate funiculus, which forms the continuation of the postero-external column of the cord and ends in the cuneate nucleus; external arcuate fibres, which arise from the gracile and cuneate fasciculi, pass through the arcuate nucleus, and join the restiform body; fibres rising from the anterior and lateral columns of the cord; fillet, which arises from the gracile and cuneate nuclei passes through the pons to the corpora quadrigemina, optic thalamus, and cortex of the cerebrum; and collections of gray matter, oh which the principal, besides the cuneate, gracile, and arcuate nuclei, are the olivary nucleus in the olivary body, and the nuclei of the last eight cranial nerves on or beneath the floor of the fourth ventricle. The m., besides connecting the cord with the brain, contains centres presiding over respiration, deglutition, vomiting, vaso-motor action, etc.

[Latin] See Myelin (1st def.).

[Latin] The mass of epidermal elements forming the central part of the axis of a hair.

[Latin] The pyramids of the kidney.

[Latin] The interior portion of the suprarenal body.