Caecum and appendix. Artwork of the junction between the small and large intestines. At centre right is the ileum, part of the small intestine. Sectioned at left is the caecum, the start of the large intestine and at bottom is the appendix. At the centre of the caecum is the ileocecal valve, the point at which the ileum joins the caecum. The caecum has a muscular wall that contracts to squeeze its contents. There are also folds in the wall to increase the surface area for the absorpstion of water from the digested food. The appendix is a blind-ended tube with no known function in humans.