clasp-knife reflexclasp-knife rigidity increased tension in the extensor of a joint when it is passively flexed, giving way suddenly on exertion of further pressure; seen especially in upper motor neuron disease. Found on http://www.encyclo.co.uk/local/21001
clasp-knife reflexclasp-knife rigidity increased tension in the extensor of a joint when it is passively flexed, giving way suddenly on exertion of further pressure; seen especially in upper motor neuron disease.