STUDIES ON THE FUNCTION OF THE INTESTINAL MUSCULATURE.—I. THE NORMAL MOVEMENTS OF THE SMALL INTESTINE AND THE RELATIONS BETWEEN THE ACTION OF THE LONGITUDINAL AND CIRCULAR MUSCLE FIBRES IN THOSE MOVEMENTS

¹ Department of Physiology, Medical College, Madras

The normal movements of the small intestine, observed when the abdomen of an anæsthetised animnal is opened under suitable conditions, are described.

Methods for recording graphically the simultaneous action of the two muscular coats in segmenting and peristaltic movements are described.

It is concluded that in the movements of the bowel there is no synchronous action of the two muscle layers, but a reciprocal action and inhibition, i. e. when the circular muscle contracts in a segment the longitudinal muscle relaxes, and vice versa. The pendulum movements are considered to be only longitudinal muscle phenomena. In peristalsis there is a wave of longitudinal muscle contraction with the circular muscle relaxed, ahead of a wave of circular muscle contraction with the longitudinal muscle relaxed. The "law" of Bayliss and Starling is applicable only to the action of the circular muscle layer.