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A hypnic jerk, hypnagogic jerk, sleep start, sleep twitch, myoclonic jerk, or night start is a brief and sudden involuntary contraction of the muscles of the body which occurs when a person is beginning to fall asleep, often causing the person to jump and awaken suddenly for a moment.
A spasm is a sudden involuntary contraction of a muscle, [1] a group of muscles, or a hollow organ, such as the bladder. A spasmodic muscle contraction may be caused by many medical conditions, including dystonia. Most commonly, it is a muscle cramp which is accompanied by a sudden burst of pain. A muscle cramp is usually harmless and ceases ...
Cadaveric spasm can be distinguished from rigor mortis as the former is a stronger stiffening of the muscles that cannot be easily undone, while rigor mortis can. [ 2 ] The cause is unknown but is usually associated with violent deaths under extreme physical circumstances with intense emotion , such as the circumstances associated with death ...
Benign fasciculation syndrome (BFS) is characterized by fasciculation (twitching) of voluntary muscles in the body. [1] The twitching can occur in any voluntary muscle group but is most common in the eyelids, arms, hands, fingers, legs, and feet.
Spasmodic dysphonia, also known as laryngeal dystonia, is a disorder in which the muscles that generate a person's voice go into periods of spasm. [1] [2] This results in breaks or interruptions in the voice, often every few sentences, which can make a person difficult to understand. [1]
The sudden jerks and twitching of the body can often be so severe that it can cause a small child to fall. A myoclonic seizure (myo "muscle", clonic "jerk") is a sudden involuntary contraction of muscle groups. The muscle jerks consist of symmetric, mostly generalized jerks, localized in the arms and in the shoulders and also simultaneously ...
A cramp is a sudden, involuntary, painful skeletal muscle contraction [1] [2] or overshortening associated with electrical activity; [3] while generally temporary and non-damaging, they can cause significant pain and a paralysis-like immobility of the affected muscle.
Deeper areas of contraction can be detected by electromyography (EMG) testing, though they can happen in any skeletal muscle in the body. Fasciculations arise as a result of spontaneous depolarization of a lower motor neuron leading to the synchronous contraction of all the skeletal muscle fibers within a single motor unit.