(Botany) an association of a fungus and a plant in which the fungus lives within or on the outside of the plant's roots forming a symbiotic or parasitic relationship. See ectotrophic mycorrhiza, endotrophic mycorrhiza. [C19: from myco- + Greek rhiza root]
Medical Definition of POSTERIOR MEDIAN SULCUS. : a shallow groove along the midline of the posterior part of the spinal cord that separates the two posterior funiculi and is the external boundary of the posterior median septum. a shallow groove along the midline of the posterior part of the spinal cord that separates the two posterior funiculi and is the external boundary of the posterior median septum.
Median Nerve. descends through the arm to the anterior forearm, where it gives off branches to the skin and to most flexor muscles. Upon reaching the hand, it innervates five intrinsic muscles of the lateral palm. This nerve activates muscles that pronate the forearm, flex the wrist/fingers and oppose the thumb. Ulnar Nerve.