The MRC scale for muscle power was first published in 1943 in a document called ‘Aids to the Investigation of Peripheral Nerve Injuries (War Memorandum No. 7)’. This became a standard text resource which was reprinted many times, and is referred to widely in a number of documents and papers. In the 1970s the document was republished with the title ‘Aids to the Examination of the Peripheral Nervous System (Memorandum No. 45)’.
The muscle scale grades muscle power on a scale of 0 to 5 in relation to the maximum expected for that muscle. In a recent comparison to an analogue scale the MRC scale is more reliable and accurate for clinical assessment in weak muscles (grades 0-3) while an analogue scale is more reliable and accurate for the assessment of stronger muscles (grades 4 and 5).
Permission to reuse the MRC Muscle Scale
The MRC Muscle Scale is licensed under the Open Government Licence.
© Crown Copyright
Aids to the Examination of the Peripheral Nervous System (Memorandum No. 45) is licensed under the Open Government Licence 3.0.
You must give appropriate credit (“Used with the permission of the Medical Research Council”) and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests that the MRC endorses you or your use.
Aids to the examination of the peripheral nervous system – MRC Memorandum No.45 (superseding War Memorandum No.7)
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Last updated: 16 March 2023