(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.
Each of the pharyngeal constrictors circumscribes the posterior wall of the pharynx and inserts on the median raphe, which is a midline continuation of the buccopharyngeal fascia (see Microscopic Anatomy). The superior pharyngeal constrictor originates on the medial pterygoid plate, mandible, and base of tongue.