(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.
Anterior funiculus: Between the anterior median fissure and anterolateral sulcus (ventral root). Merges with the lateral funiculus. Contains ascending and descending tracts. Lateral funiculus: Between the dorsal and ventral roots. Merges with the anterior funiculus. Contains ascending and descending tracts. Posterior lateral sulcus: Site of entry of dorsal root. Posterior funiculus: Between posterior median sulcus and dorsal root. Contains ascending tracts.