Clasp-knife response refers to a Golgi tendon reflex with a rapid decrease in resistance when attempting to flex a joint, usually during a neurological examination. It is one of the characteristic responses of an upper motor neuron lesion. It gets its name from the resemblance between the motion of the limb and the sudden closing of a claspknife after sufficient pressure is applied.
When a joint is passively flexed, the resisting force comes from the stretch reflex (or sometimes called tendon reflex) resulting from the extensor muscle being stretched.[1] In upper motor neuron lesions, muscle tonus may increase and resistance of muscle to stretch increases. However, if sufficient force is applied, limb resistance suddenly decreases, presumably mediated by the Golgi tendon reflex (also call autogenic inhibition).[1]
Mechanismedit
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]
Exampleedit
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.
^ ab. 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.
External linksedit
January 01, 1970
clasp, knife, response, this, article, multiple, issues, please, help, improve, discuss, these, issues, talk, page, learn, when, remove, these, template, messages, this, article, needs, additional, citations, verification, please, help, improve, this, article,. This article has multiple issues Please help improve it or discuss these issues on the talk page Learn how and when to remove these template messages This article needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed Find sources Clasp knife response news newspapers books scholar JSTOR February 2015 Learn how and when to remove this message This article may be too technical for most readers to understand Please help improve it to make it understandable to non experts without removing the technical details December 2023 Learn how and when to remove this message Learn how and when to remove this message Clasp knife response refers to a Golgi tendon reflex with a rapid decrease in resistance when attempting to flex a joint usually during a neurological examination It is one of the characteristic responses of an upper motor neuron lesion It gets its name from the resemblance between the motion of the limb and the sudden closing of a claspknife after sufficient pressure is applied Contents 1 Cause 2 Mechanism 3 Example 4 See also 5 References 6 External linksCause editWhen a joint is passively flexed the resisting force comes from the stretch reflex or sometimes called tendon reflex resulting from the extensor muscle being stretched 1 In upper motor neuron lesions muscle tonus may increase and resistance of muscle to stretch increases However if sufficient force is applied limb resistance suddenly decreases presumably mediated by the Golgi tendon reflex also call autogenic inhibition 1 Mechanism editThis 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 editPassive 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 editHypertoniaReferences edit 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 External links editLib mcg edu Retrieved from https en wikipedia org w index php title Clasp knife response amp oldid 1209477896, wikipedia, wiki, book, books, library,
