(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.
(December 2009) (Learn how and when to remove this template message) The Sulcus sign is an orthopedic evaluation test for glenohumeral instability of the shoulder. With the arm straight and relaxed to the side of the patient, the elbow is grasped and traction is applied in an inferior direction. With excessive inferior translation, a depression occurs just below the acromion. The appearance of this sulcus is a positive sign.