| clasp-knife rigidity | Initial increased resistance to stretch of the extensor muscles of a joint that give way rather suddenly allowing the joint then to be easily flexed; the rigidity is due to an exaggeration of the stretch reflex. See: lengthening reaction. Synonym: clasp-knife effect, clasp-knife rigidity. (05 Mar 2000) |
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| cogwheel rigidity | <clinical sign, neurology> A type of rigidity seen in parkinsonism in which the muscles respond with cogwheel-like jerks to the use of constant force in bending the limb. (21 Jun 2000) |
| muscle rigidity | Continuous tonic contraction of skeletal muscle. (12 Dec 1998) |
| postmortem rigidity | Muscular rigidity which develops in the cadaver usually from 4 to 10 hours after death and lasts 3 or 4 days. (12 Dec 1998) |
| scleral rigidity | The resistance of the eye to changes in shape with changes in intraocular pressure. (05 Mar 2000) |
| decerebrate rigidity | <clinical sign, neurology> Spontaneous extension of elbows, wrists and legs which suggests damage to the diencephalon (midbrain). Seen in cases of stroke and some cases of encephalitis. The decerebrate reflex is a clinical finding characterised by rigid contraction of the extensor and other muscles which maintain an animal in the standing position (antigravity muscles), may be seen in association with a severe stroke, intracranial haemorrhage, cerebral haemorrhage, cerebral toxin or transection of the brain below the level of the anterior corpora quadrigemina but above the vestibular nuclei, clinically may be preceded by decortication. (27 Sep 1997) |
| decorticate rigidity | A unilateral or bilateral postural change, consisting of the upper extremities flexed and adducted and the lower extremities in rigid extension; due to structural lesions of the thalamus, internal capsule, or cerebral white matter. Synonym: decorticate state. (05 Mar 2000) |
| ocular rigidity | The resistance offered by the eyeball to a change in intraocular volume; manifested as a change in intraocular pressure. (05 Mar 2000) |
| lead-pipe rigidity | The plastic type of rigidity resembling that of a pipe of lead seen in certain forms of parkinsonism. (05 Mar 2000) |