Crossed Extension Reflex Following Withdrawal Reflex
Once a danger receptor (called 'nociceptor') has been stimulated, the signal travels via the sensory nerve to the posterior horn of the spinal cord. The nerve synapses with ipsilateral motor neurons that exit the anterior horn of the spinal cord and work to pull the injured body part away from danger within 0.5 seconds. At the same time the sensory neuron synapses with the ipsilateral motor neuron, it also synapses with the motor neuron in the contralateral anterior horn. This motor neuron stabilizes the uninjured side of the body (for instance, preparing the opposite leg to support the entire body weight when the other foot has stepped on a tack). At the same time as these two synapses, the sensory neuron also sends signals up the spinal cord to get motor neurons to contract muscles that shift the center of gravity of the body to maintain balance. This contralateral stimulation of motor neurons to stabilize the body is called the crossed extension reflex, and is a result of the withdrawal reflex (usually in the lower extremities).
Read more about this topic: Withdrawal Reflex
Famous quotes containing the words crossed, extension, reflex and/or withdrawal:
“I had crossed de line of which I had so long been dreaming. I was free; but dere was no one to welcome me to de land of freedom. I was a stranger in a strange land, and my home after all was down in de old cabin quarter, wid de ole folks, and my brudders and sisters. But to dis solemn resolution I came; I was free, and dey should be free also; I would make a home for dem in de North, and de Lord helping me, I would bring dem all dere.”
—Harriet Tubman (c. 1820–1913)
“The motive of science was the extension of man, on all sides, into Nature, till his hands should touch the stars, his eyes see through the earth, his ears understand the language of beast and bird, and the sense of the wind; and, through his sympathy, heaven and earth should talk with him. But that is not our science.”
—Ralph Waldo Emerson (1803–1882)
“As a medium of exchange,... worrying regulates intimacy, and it is often an appropriate response to ordinary demands that begin to feel excessive. But from a modernized Freudian view, worrying—as a reflex response to demand—never puts the self or the objects of its interest into question, and that is precisely its function in psychic life. It domesticates self-doubt.”
—Adam Phillips, British child psychoanalyst. “Worrying and Its Discontents,” in On Kissing, Tickling, and Being Bored, p. 58, Harvard University Press (1993)
“A bizarre sensation pervades a relationship of pretense. No truth seems true. A simple morning’s greeting and response appear loaded with innuendo and fraught with implications.... Each nicety becomes more sterile and each withdrawal more permanent.”
—Maya Angelou (b. 1928)