The caecocolonic junction in humans has a sphincteric anatomy and function

Area of Science:

• Gastroenterology
• Human Anatomy
• Functional Morphology

Background:

• Mammalian caecocolonic junctions exhibit sphincteric anatomy and function.
• Human radiologists and endoscopists have reported a distinct ileocaecal fold, but anatomical and microscopic studies yielded conflicting results.

Purpose of the Study:

• To confirm the existence of a specialized fold at the human caecocolonic junction.
• To ascertain the functional role of this fold through a functional anatomy study.

Main Methods:

• Pancolonoscopies were performed on 100 patients to observe ileocaecal fold behavior before and after mechanical stimulation.
• Surgically obtained ileocaecocolonic regions were studied macroscopically and microscopically after fixation and stimulation.

Main Results:

• Endoscopic observation revealed a semilunar or circular ileocaecal fold, with spasms noted in 52% of patients.
• Stimulation revealed a prominent circular fold in surgical specimens, with the muscle coat deeply penetrating it.
• Microscopic analysis showed a unique, thickened arrangement of the inner circular muscle within the fold, characteristic of the ileocaecal junction.

Conclusions:

• The human caecocolonic junction demonstrates sphincter-like morphology and function.
• The physiological relevance of this sphincter in ileal flow and cecal function warrants further investigation, particularly concerning colonic motility disorders.