This section is from the book "Diseases Of The Intestines", by Max Einhorn. Also available from Amazon: Diseases Of The Intestines A Text-Book For Practitioners And Students Of Medicine.
While normally no sensations originate in the intestinal canal which become perceptible even during digestion, in pathological conditions this organ may be the seat of the most painful feelings. The latter originate in the fibres of the sympathetic nerve. Most of the sensory neuroses of the intestine consist in an increased excitability of the sen-sorv filaments of these nerves. There are, however, a few conditions in which a lessened sensibility exists. The latter relates principally to the sensory nerves of the rectum. Normally the entrance of fecal matter into the rectum mechanically irritates these nerves and creates a desire for an evacuation, while a lessened irritability of the rectal nerves may fail to produce the above sensation.