Clasp-knife response
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Clasp-knife response refers to a
Cause
When a joint is passively flexed, the resisting force comes from the
Mechanism
This reflex is observed in patients with upper motor neuron lesions. It was frequently attributed to the action of the golgi tendon organ, likely because of early studies showing that tendon organs are activated by strong muscle stretch and inhibit motor neurons of the stretched muscle. It was thought that this was a protective reflex, preventing application of so much force that muscles become damaged. More recent work strongly suggests that tendon organs are not involved in the clasp knife reflex, but that other sensory receptors in muscles are responsible.[2]
Example
Passive flexion of elbow meets immediate resistance due to stretch reflex in the triceps muscle. Further stretch activates inverse stretch reflex. The resistance to flexion suddenly collapses, and the elbow flexes. Continued passive flexion stretches the muscle and the sequence may be repeated.
As the muscle tone increases, resistance against flexion of the limb increases as well. However, when flexion is continued, further stretching of the triceps muscle activates an inverse stretch reflex that relaxes the muscle due to autogenic inhibition.
See also
References
- ^ a b "Spinal Relexes". Musom.marshall.edu. Archived from the original on 3 March 2016. Retrieved 23 February 2015.
- ^ Neural mechanisms underlying the clasp-knife reflex in the cat. I. Characteristics of the reflex. Cleland CL, Rymer WZ. J Neurophysiol. 1990 Oct;64(4):1303-18. Spasticity, decerebrate rigidity and the clasp-knife phenomenon: an experimental study in the cat. Burke D, Knowles L, Andrews C, Ashby P. Brain. 1972;95(1):31-48.