(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 portion of the pharynx located posterior to the posterior nasal apertures and superior to the soft palate. nasopharynx communicates; anteriorly with the nasal cavity through the choanae and inferiorly with the oropharynx; it contains the torus tubarius, pharyngeal recess and pharyngeal tonsil.he portion of the pharynx located posterior to the posterior nasal apertures and superior to the soft palate. nasopharynx communicates; anteriorly with the nasal cavity through the choanae and inferiorly with the oropharynx; it contains the torus tubarius, pharyngeal recess and pharyngeal tonsil.