(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.
The posterior column (dorsal column) refers to the area of white matter in the middle to posterior side of the spinal cord.t is made up of the gracile fasciculus and the cuneate fasciculus and itself is part of the posterior funiculus. It is part of an ascending pathway that is important for well-localized fine touch and conscious proprioception called the posterior column-medial lemniscus pathway.