Bell-Magendie Law
Historical document, translated for reference. It reflects medical knowledge of the 1920s–30s and is not medical advice.
Summary
The Bell-Magendie Law states that cutting the anterior roots of the spinal cord causes paralysis of voluntary muscles, while cutting the posterior roots causes anesthesia in corresponding body parts. This is because the fibers in the anterior roots are centrifugal/motor, while those in the posterior roots are centripetal/sensory.
Encyclopedia entry (1928–1936)
Bell-Magendie Law consists in the fact that the severance of the anterior roots of the spinal cord leads to paralysis of the voluntary musculature, while the severance of the posterior roots causes anesthesia in the corresponding parts of the body, because the fibers that make up the anterior roots are centrifugal, motor, and the fibers of the posterior roots are centripetal, sensory. This law is confirmed by experiments with electrical irritation of a severed root: irritation of the peripheral segment of the anterior root causes muscle contraction; of the central segment remains without any motor effect; in experiments on the posterior root the opposite occurs - pain is caused by irritation of the central segment, while irritation of the peripheral segment remains painless.
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“Bell-Magendie Law.” Soviet Medical Encyclopedia. English translation of Bolshaya Meditsinskaya Entsiklopediya, 1st ed. (Moscow, 1928–1936), ed. N. A. Semashko. https://sovietmedicalencyclopedia.pages.dev/article/bell-magendie-law/