Tetanic contraction
Encyclopedia
A tetanic contraction occurs when a motor unit
has been maximally stimulated by its motor neuron
. This occurs when a muscle's motor unit is stimulated at a sufficiently high frequency of multiple impulses. Each stimulus causes a twitch. If stimuli are delivered slow enough, the tension in the muscle will relax between successive twitches. If stimuli is delivered at high frequency, then the twitches will add up, resulting in tetanic contraction. When tetanized, the contracting tension in the muscle remains constant in a steady state
. This is the maximal contraction.
Tetanic contraction may also occur as part of an extrapyramidal
adverse drug reaction
of some typical antipsychotic
drugs, specifically the opisthotonos effect of acute dystonic reaction in which "tetanic" heightening of entire body, head and belly up occurs. Tetanic contraction may be observed following the use of a device intended to apply transcutaneous electrical muscle stimulation
(EMS) through skin contact electrodes for the purpose of improving abdominal muscle tone.
, due to an underdeveloped parathyroid, or injury to the parathyroid
.
Motor unit
”A motor unit is a single α-motor neuron and all of the corresponding muscle fibers it innervates; all of these fibers will be of the same type . When a motor unit is activated, all of its fibers contract...
has been maximally stimulated by its motor neuron
Motor neuron
In vertebrates, the term motor neuron classically applies to neurons located in the central nervous system that project their axons outside the CNS and directly or indirectly control muscles...
. This occurs when a muscle's motor unit is stimulated at a sufficiently high frequency of multiple impulses. Each stimulus causes a twitch. If stimuli are delivered slow enough, the tension in the muscle will relax between successive twitches. If stimuli is delivered at high frequency, then the twitches will add up, resulting in tetanic contraction. When tetanized, the contracting tension in the muscle remains constant in a steady state
Steady state
A system in a steady state has numerous properties that are unchanging in time. This implies that for any property p of the system, the partial derivative with respect to time is zero:...
. This is the maximal contraction.
Tetanic contraction may also occur as part of an extrapyramidal
Extrapyramidal
Extrapyramidal can refer to:* Extrapyramidal system* Extrapyramidal symptoms...
adverse drug reaction
Adverse drug reaction
An adverse drug reaction is an expression that describes harm associated with the use of given medications at a normal dosage. ADRs may occur following a single dose or prolonged administration of a drug or result from the combination of two or more drugs...
of some typical antipsychotic
Typical antipsychotic
Typical antipsychotics are a class of antipsychotic drugs first developed in the 1950s and used to treat psychosis...
drugs, specifically the opisthotonos effect of acute dystonic reaction in which "tetanic" heightening of entire body, head and belly up occurs. Tetanic contraction may be observed following the use of a device intended to apply transcutaneous electrical muscle stimulation
Electrical muscle stimulation
Electrical muscle stimulation , also known as neuromuscular electrical stimulation or electromyostimulation, is the elicitation of muscle contraction using electric impulses...
(EMS) through skin contact electrodes for the purpose of improving abdominal muscle tone.
Diseases
Tetanic contractions are a symptom of hypoparathyroidismHypoparathyroidism
Hypoparathyroidism is decreased function of the parathyroid glands with under production of parathyroid hormone. This can lead to low levels of calcium in the blood, often causing cramping and twitching of muscles or tetany , and several other symptoms...
, due to an underdeveloped parathyroid, or injury to the parathyroid
Parathyroid gland
The parathyroid glands are small endocrine glands in the neck that produce parathyroid hormone. Humans usually have four parathyroid glands, which are usually located on the rear surface of the thyroid gland, or, in rare cases, within the thyroid gland itself or in the chest...
.