myasthenia

myasthenia /mī′əsthē″nē·ə/ [Gk, mys + a + sthenos, without strength] , a condition characterized by an abnormal weakness of a muscle or a group of muscles that may be the result of a systemic myoneural disturbance, such as in myasthenia laryngis, which involves the vocal cord tensor muscles. See also myasthenia gravis.myasthenic, adj.