Patterns of response of the paravertebral musculature to visceral stimuli.

Abstract

Stimulation of abdominal viscera provokes reflex contractions of the paravertebral muscles. The reflex contractions change in intensity and in number of segments involved with variations in degree of stimulus. With minimal stimuli the response is limited to two or three segments. With increasing intensity of stimuli the response spreads to include adjacent segments and can extend to the contralateral side. Such visceromotor reflexes have been shown for the renal pelvis, ureter, small intestine and fallopian tube. When an unpaired organ such as the intestine is stimulated, the response is bilateral even to minimal stimuli. To a prolonged stimulus there is a build-up to a peak activity followed by a decrease which is then maintained for variable periods from seconds to hours. Such prolonged activity also frequently follows very brief stimuli. The influences of drugs and other stimuli on these visceromotor reflexes are demonstrated.