Marker. 1  Noun. A line of credit extended by a casino or cardroom. 2  Noun. A small object placed on top of a player's hand for the purpose of preventing it from being mucked or fouled. 3  Noun. A plastic device used to denote who is in the dealer's position.
Myasthenia gravis is caused by a defect in the transmission of nerve impulses to muscles. It occurs when normal communication between the nerve and muscle is interrupted at the neuromuscular junction -- the place where nerve cells connect with the muscles they control.
Email. Print. Myasthenia gravis is a neuromuscular disorder that causes weakness and fatigue in the muscles that control voluntary movement in the body. The weakness is caused by a disruption in the communication between the muscles and the nerves that control them.hile myasthenia gravis can affect any voluntary muscles in the body, most patients will first notice its effects in the muscles that control the movement of the eyes and eyelids. The weakening of these muscles can result in droopy eyelids, double vision and partial paralysis of eye movements.