\Med"ul*la*ry\, a. [L. medullaris, fr. medulla marrow:
cf. F. m['e]dullaire.]
1. (Anat.)
   (a) Pertaining to, consisting of, or resembling, marrow or
       medulla.
   (b) Pertaining to the medula oblongata.
2. (Bot.) Filled with spongy pith; pithy.
{Medullary groove} (Anat.), a groove, in the epiblast of the
   vertebrate blastoderm, the edges of which unite, making a
   tube (the medullary canal) from which the brain and spinal
   cord are developed.
{Medullary rays} (Bot.), the rays of cellular tissue seen in
   a transverse section of exogenous wood, which pass from
   the pith to the bark.
{Medullary sheath} (Anat.), the layer of white semifluid
   substance (myelin), between the primitive sheath and axis
   cylinder of a medullated nerve fiber.