A spasm is a sudden involuntary
contraction of a
muscle
Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of muscl ...
,
a group of muscles, or a hollow
organ
Organ may refer to:
Biology
* Organ (biology), a part of an organism
Musical instruments
* Organ (music), a family of keyboard musical instruments characterized by sustained tone
** Electronic organ, an electronic keyboard instrument
** Hammond ...
such as the bladder.
A spasmodic muscle contraction may be caused by many medical conditions, including
dystonia
Dystonia is a neurological hyperkinetic movement disorder in which sustained or repetitive muscle contractions result in twisting and repetitive movements or abnormal fixed postures. The movements may resemble a tremor. Dystonia is often inten ...
. Most commonly, it is a
muscle cramp which is accompanied by a sudden burst of pain. A muscle cramp is usually harmless and ceases after a few minutes. It is typically caused by
ion imbalance or
muscle overload
Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of muscle ...
.
There are other causes of involuntary muscle contractions, and some of these may cause a
health problem.
Description and causes
Various kinds of involuntary muscle activity may be referred to as a "spasm".
A spasm may be a muscle contraction caused by abnormal nerve stimulation or by abnormal activity of the muscle itself.
A spasm may lead to muscle strains or tears in
tendons and
ligaments if the force of the spasm exceeds the tensile strength of the underlying connective tissue. This can occur with a particularly strong spasm or with weakened connective tissue.
A
hypertonic muscle spasm is a condition of chronic, excessive
muscle tone
In physiology, medicine, and anatomy, muscle tone (residual muscle tension or tonus) is the continuous and passive partial muscle contraction, contraction of the muscles, or the muscle's resistance to passive stretch during resting state.O’Sull ...
(i.e., tension in a resting muscle). This is the amount of contraction that remains when a muscle is not working. A true
hypertonic spasm is caused by malfunctioning feedback nerves. This is much more serious and is permanent unless treated. In this case, the hypertonic muscle tone is excessive, and the muscles are unable to relax.
A subtype of spasm is
colic. This is an episodic pain caused by spasm of
smooth muscle
Smooth muscle is an involuntary non-striated muscle, so-called because it has no sarcomeres and therefore no striations (''bands'' or ''stripes''). It is divided into two subgroups, single-unit and multiunit smooth muscle. Within single-unit mus ...
in a particular organ (e.g., the
bile duct). A characteristic of colic is the sensation of having to move about, and the pain may induce
nausea or
vomiting.
See also
*
Antispasmodic
*
Blepharospasm
*
Cadaveric spasm
*
Convulsion
*
Cramp
*
Cricopharyngeal spasm
*
Ejaculation
*
Epileptic seizure
*
Jactitation (medicine)
*
Myoclonus
*
Neck spasm
*
Orgasm
*
Spasmodic dysphonia
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. This results in breaks or interruptions in the voice, often every few sentences, which can make a pe ...
*
Spasticity
References
External links
NIH Medical Encyclopedia*
{{Authority control
Symptoms and signs: Nervous and musculoskeletal systems