(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.
Posterior white columns lie between the posterior gray horns and theposterior median sulcus.2. Anterior white columns lie between the anterior gray horns and theanterior median fissure. (Axons cross from one side of the spinal cord tothe other in the anterior white commissure.). 3.xplain the roles of white matter and gray matter in processing and relayingsensory information and motor commands. Figure 13-2 â¢ The adult spinal cord is about 18 inches (45 cm) long and 1/2 inch (14 mm) wide.It ends between vertebrae L1 and L2.â¢ The groove on the posterior side is the posterior median sulcus.