| crossed embolism | Passage of a clot (thrombus) from a vein to an artery. When clots in veins break off (embolise) , they travel first to the right side of the heart and, normally, then to the lungs where they lodge. The lungs act as a filter to prevent the clots from entering the arterial circulation. However, when there is a hole in the wall between the two upper chambers of the heart (an atrial septal defect), a clot can crossparadoxically from the right to the left side of the heart, then pass into the arteries. Once in the arterial circulation, a clot can travel to the brain, block a vessel there, and cause a stroke (cerebrovascular accident). Because of the risk of stroke from crossed embolism, it is usually recommended that even small atrial septal defects be closed (repaired). Also called: paradoxical embolism. (12 Dec 1998) |
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| crossed extension reflex | Extension of the contralateral hind limb when the paw of an animal is painfully stimulated or the central cut end of an afferent nerve, e.g., the peroneal, is stimulated; sometimes occurs in humans upon tapping the skin. (05 Mar 2000) |
| crossed eyes | <clinical sign> A deviation of the eye which the patient cannot overcome. The visual axes assume a position relative to each other different from that required by the physiological conditions. The various forms of strabismus are spoken of as tropias, their direction being indicated by the appropriate prefix, as cyclo tropia, esotropia, exotropia, hypertropia and hypotropia. Also called cast, heterotropia, manifest deviation and squint. Origin: Gr. Strabismos = a squinting (18 Nov 1997) |
| crossed fixation | In convergent strabismus, the use of the right inturned eye to look at objects to the left and the left inturned eye to look at objects to the right, in order to avoid ocular rotation. (05 Mar 2000) |
| crossed hemianesthesia | alternate hemianesthesia |
| crossed hemianopia | Attitudinal hemianopia involving the upper field of one eye and the lower field of the other; or a binasal or bitemporal hemianopia. Synonym: crossed hemianopia. (05 Mar 2000) |
| crossed hemiplegia | alternating hemiplegia |
| crossed immunoelectrophoresis | two-dimensional immunoelectrophoresis |
| crossed knee reflex | Contraction of the contralateral quadriceps when a patellar reflex is elicited. Synonym: crossed knee jerk. (05 Mar 2000) |
| crossed paralysis | alternating hemiplegia |
| crossed phrenic phenomenon | Hemisection of the cord above the exit of the phrenic nerve paralyzes the ipsilateral half of the diaphragm; if the contralateral phrenic nerve is then sectioned or blocked, contractions on the ipsilateral side are resumed. (05 Mar 2000) |
| crossed pyramidal tract | Those fibres of the pyramidal tract that cross to the opposite side in the pyramidal decussation and descend in the dorsal half of the lateral funiculus of the spinal cord; they are distributed throughout the length of the spinal cord to interneurons of the zona intermedia of the spinal gray matter. See: pyramidal tract. Synonym: tractus corticospinalis lateralis, tractus pyramidalis lateralis, crossed pyramidal tract, fasciculus corticospinalis lateralis, fasciculus pyramidalis lateralis, lateral corticospinal tract, lateral pyramidal fasciculus. (05 Mar 2000) |
| crossed reflex | A reflex movement on one side of the body in response to a stimulus applied to the opposite side. Synonym: crossed jerk. (05 Mar 2000) |
| crossed reflex of pelvis | Contraction of the contralateral adductors of the thigh upon tapping the anterior superior iliac spine. Synonym: crossed spino-adductor reflex. (05 Mar 2000) |
| crossed renal ectopia | <radiology> M more than F, right (67%), may fuse: crossed-fused renal ectopia (12 Dec 1998) |