- 1. A shortening or increase in tension; denoting the normal function of muscle. 2. A shrinkage or reduction in size. 3. Heart beat, as in premature c..beat. [L. contractus, drawn together]- after-c. aftercontraction.- anodal closure c. (ACC, AnCC) obsolete term for the momentary c. of a muscle under the influence of the positive pole when the electrical circuit is established.- anodal opening c. (AnOC, AOC) obsolete term for the momentary c. of a muscle under the influence of the positive pole when the circuit is broken.- automatic c. SYN: automatic beat.- Braxton Hicks c. rhythmic myometrial activity occurring during the course of a pregnancy that usually causes no pain for the patient.- cathodal closure c. (CaCC, CCC) obsolete term for the momentary c. of a muscle under the influence of the negative pole when an electrical circuit is established.- cathodal opening c. (CaOC, COC) obsolete term for the momentary c. of a muscle under the influence of the negative pole when the circuit is broken.- closing c. c. produced at the time of closing of the circuit when using direct current to stimulate the muscle.- fibrillary contractions contractions occurring spontaneously in individual muscle fibers; they are seen commonly a few days after damage to the motor nerves supplying the muscle, and this type of activity is distinguished from fasciculation, which is related to activation of motor units.- front-tap c. c. of the calf muscles when the anterior surface of the leg is struck. SYN: Gowers c..- Gowers c. SYN: front-tap c..- hourglass c. constriction of the middle portion of a hollow organ, such as the stomach or the gravid uterus.- myotatic c. a reflex c. of a skeletal muscle that occurs as a result of stimulation of the stretch receptors in the muscle, i.e., as part of a myotatic reflex.- opening c. a c. produced at the time of opening the circuit when using direct current to stimulate the muscle or a motor nerve.- paradoxical c. a tonic c. of the anterior tibial muscles when a sudden passive dorsal flexion of the foot is made.- reflex detrusor c. normal coordinated function of the bladder with sustained contractions of the bladder matched by simultaneous relaxation of the sphincteric outlet mechanisms to empty the bladder.
* * *con·trac·tion kən-'trak-shən n1) the action or process of contracting: the state of being contracted <\contraction of hepatitis> <lung expansion and \contraction in breathing (P. G. Donohue)>2) the action of a functioning muscle or muscle fiber in which force is generated accompanied esp. by shortening and thickening of the muscle or muscle fiber or sometimes by its lengthening <isometric \contraction> <isotonic \contraction> esp the shortening and thickening of a functioning muscle or muscle fiber3) one of usu. a series of rhythmic tightening actions of the uterine muscles (as during menstruation or labor)
* * *n.the shortening of a muscle in response to a motor nerve impulse. This generates tension in the muscle, usually causing movement.
* * *con·trac·tion (kən-trakґshən) [L. contractus drawn together] 1. a reduction in size or shrinkage. 2. in muscle, an increase in tension that may or may not shorten the muscle. 3. abnormal approximation of mandibular and maxillary structures to the median plane. See also distraction (def. 5).
Medical dictionary. 2011.