Medulla

Medulla is the term used in anatomy and botany to denote the inner or central part of an organ or structure. The word derives from Latin medulla, meaning marrow or innermost part.

Anatomy and medicine: The medulla oblongata is the lower portion of the brainstem, continuous with the spinal cord at the foramen magnum. It houses essential autonomic centers that regulate cardiovascular and respiratory function and contains several cranial nerve nuclei. It also includes centers involved in reflexes such as coughing, swallowing, and vomiting. The medulla is a critical conduit for ascending and descending neural pathways, and damage to it can be life-threatening due to disruption of basic autonomic control.

Renal medulla: The renal medulla is the inner portion of the kidney, surrounding the renal pelvis and shaped by renal pyramids. It contains parts of the nephron such as segments of the loop of Henle and the collecting ducts, contributing to urine concentration. The medulla operates within the renal countercurrent mechanism to maintain systemic fluid and electrolyte balance, aided by the vasa recta blood vessels.

Adrenal medulla: The adrenal medulla is the inner region of the adrenal gland. It consists of chromaffin cells that secrete catecholamines (epinephrine and norepinephrine) into the bloodstream in response to sympathetic stimulation, forming part of the body’s fight-or-flight response. It is innervated by preganglionic sympathetic fibers and functions as a neuroendocrine organ.

Botany: In plants, medulla denotes the inner tissue of certain organs, such as stems, roots, or seeds, forming a central region that is typically composed of living parenchyma cells. The exact structure and role of the medulla vary among species and organ types.