What Crosses Our Minds When Danger's Afoot[ ... Read the full article ... ]
By David Brown
Washington Post Staff Writer
Monday, June 13, 2005; Page A08
One of the more mysterious and less-explored observations about human anatomy is also one of the oldest, going all the way back to the Father of Medicine.
"If the wound be situated on the left side [of the head], the convulsion attacks the right side of the body," Hippocrates noted in the 4th century B.C. The Greek physician recognized that trauma on one side of the head could cause a seizure limited to or, more likely, starting in the limbs on the opposite side of the body.
About A.D. 150, a physician named Aretaeus the Cappadocian extended this observation in a truly remarkable way.
He noticed that if the right side of the head was severely damaged, the left side of the body would be paralyzed. However, if the damage was in the right side of the spinal cord instead, the paralysis would be on the same side. He then came up with an explanation.
"The cause of this is the interchange in the origins of the nerves, for they do not pass along on the same side . . . until their terminations," he wrote, according to an account in the 1994 book "Origins of Neuroscience" by medical historian Stanley Finger. Each nerve "passes over to the other side from that of its origin, [separating from] each other in the form of the letter X."
Anthony H. Risser | neuroscience | neuropsychology | brain