(kŏn-trak′shŏn )

[L. contractio, a drawing together]
A shortening or tightening, as of a muscle; a shrinking or a reduction in size.

Braxton Hicks contraction

SEE: Braxton Hicks contractions

concentric muscle contraction

Contraction of a muscle in which the extended muscle is shortened. Pulling the body up by grasping a bar over the head is such a contraction.

eccentric muscle contraction

Lengthening of the muscle as it contracts against resistance. Lowering the body from a position in which the body was supported by the flexed arms, i.e., holding onto a bar above the head, is such a contraction.

hourglass contraction

An excessive, irregular contraction of an organ at its center.
SEE: ectasia

idiomuscular contraction

Motion produced by degenerated muscles without nerve stimulus.

incoordinate uterine contraction

An abnormality of the first stage of labor in which uterine contractions are too weak or too ineffective to dilate the cervix.

interdigestive migrating contractions

SEE: Migrating motor complex.

isometric contraction

A muscular contraction in which the muscle increases tension but does not change its length.
SYN: SEE: static muscle contraction

isotonic contraction

A muscular contraction in which the muscle maintains constant tension by changing its length during the action.

premature ventricular contraction

ABBR: PVC Contraction of the cardiac ventricle before the normal time, caused by an electrical impulse to the ventricle arising from a site other than the sinoatrial node. The PVC may be a single event or may occur several times a minute or in pairs or strings. Three or more PVCs in a row constitute ventricular tachycardia.

static muscle contraction

SEE: Isometric contraction.

tetanic contraction

1. Continuous muscular contraction.
2. A sudden, strong, sustained uterine contraction that jeopardizes maternal and fetal status. It may occur during oxytocin induction or stimulation of labor and can cause profound fetal distress, premature placental separation, or uterine rupture.

tonic contraction

Spasmodic contraction of a muscle for an extended period.

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