| hourglass contraction | Constriction of the middle portion of a hollow organ, such as the stomach or the gravid uterus. (05 Mar 2000) |
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| hourglass head | In congenital syphilis, a skull with depressed coronal suture. (05 Mar 2000) |
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| hourglass murmur | One in which there are two areas of maximum loudness decreasing to a point midway between the two. (05 Mar 2000) |
| hourglass pattern | A vigorous ringlike contraction observed angiographically in the left ventricular angiogram in the right anterior oblique projection, resembling an hourglass; it is seen in the prolapsed mitral valve leaflet syndrome. (05 Mar 2000) |
| hourglass stomach | A condition in which there is a central constriction of the wall of the stomach dividing it into two cavities, cardiac and pyloric. Synonym: bilocular stomach, ectasia ventriculi paradoxa. Leather-bottle stomach, marked thickening and rigidity of the stomach wall, with reduced capacity of the lumen although often without obstruction; nearly always due to scirrhous carcinoma, as in linitis plastica. Synonym: sclerotic stomach. (05 Mar 2000) |
| hourglass vertebrae | The radiographic appearance of some vertebrae in osteogenesis imperfecta tarda. (05 Mar 2000) |
| anodal closure contraction | An obsolete term for the momentary contraction of a muscle under the influence of the positive pole when the electrical circuit is established. (05 Mar 2000) |
| anodal opening contraction | An obsolete term for the momentary contraction of a muscle under the influence of the positive pole when the circuit is broken. (05 Mar 2000) |
| atrial premature contraction | <cardiology> An premature heartbeat of atrial origin. Generally nonserious and typically exacerbated by stimulant use (for example alcohol, decongestants, caffeine, nicotine). (27 Sep 1997) |
| automatic contraction | In contrast to forced beat, an ectopic beat that arises de novo and is not precipitated by the preceding beat; thus escaped and parasystolic beat's are automatic. Synonym: automatic contraction. (05 Mar 2000) |
| braxton hicks contraction | Rhythmic uterine muscle activity which occurs during the course of a pregnancy which causes no pain for the patient. (27 Sep 1997) |
| paradoxical contraction | A tonic contraction of the anterior tibial muscles when a sudden passive dorsal flexion of the foot is made. (05 Mar 2000) |
| carpopedal contraction | <clinical sign> Spasms of the hands or feet that may be seen in association with hypocalcaemia or hyperventilation. (08 Jan 1998) |
| reflex detrusor contraction | 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. (05 Mar 2000) |
| cathodal closure contraction | An obsolete term for the momentary contraction of a muscle under the influence of the negative pole when an electrical circuit is established. (05 Mar 2000) |
| cathodal opening contraction | An obsolete term for the momentary contraction of a muscle under the influence of the negative pole when the circuit is broken. (05 Mar 2000) |