Study of the functional activity of the cecocolonic junction with identification of a ``physiologic sphincter{''}, ``cecocolonic inhibitory reflex{''} and ``colocecal excitatory reflex{''

Radiologic, endoscopic and histomorphologic studies have suggested the presence of a sphincter at the cecocolonic junction (CCJ), while some investigators have denied its existence. To investigate the physiologic activity at the CCJ, the right colon was exposed during right hemicolectomy for early colonic cancer in 11 patients (mean age 43.6+/-12.3 years; 8 men). Three manometric catheters were introduced through colotomy to be separately located in the cecum, CCJ and ascending colon. We determined the CCJ pressure response to cecal and colonic distension by means of a balloon filled with saline in increments of 10 ml. The test was repeated after individual anesthetization of cecum, CCJ and ascending colon. The CCJ measured 1.6+/-0.6 cm in length and had a higher pressure (p<0.05) than the cecum or colon. Large-volume cecal distension effected a significant CCJ pressure reduction which was augmented as the distension increased. Latency decreased upon increase of the distending volume. In contrast, the CCJ responded to large-volume colonic distension by pressure elevation which increased upon increase of the distending volume. Latency diminished with increased distension. Small-volume cecal or colonic distension effected no CCJ pressure response. The anesthetized CCJ did not respond to distension of the cecum or colon. Likewise, the CCJ did not exhibit a pressure response to distension of the anesthetized cecum or colon. The CCJ is a high-pressure zone which reacts to cecal or colonic distension by dilatation or narrowing, respectively. These data presumably denote the existence of a physiologic sphincter at the CCJ. We suggest that the CCJ pressure response to cecal or colonic distension is reflex and mediated through the cecocolonic inhibitory and colocecal excitatory reflexes, respectively. The role of the CCJ and related reflexes in colonic motility disorders needs to be studied.