The appendix is a narrow, hollow, blind-ended tube connected to the cecum. It has large aggregations of lymphoid tissue in its walls and is suspended from the terminal ileum by the mesoappendix (Fig. 4.83), which contains the appendicular vessels. Its point of attachment to the cecum is consistent with the highly visible free taeniae leading directly to the base of the appendix, but the location of the rest of the appendix varies considerably (Fig. 4.84). It may be: posterior to the cecum or the lower ascending colon, or both, in a retrocecal or retrocolic position; suspended over the pelvic brim in a pelvic or descending position; below the cecum in a subcecal location; or anterior to the terminal ileum, possibly contacting the body wall, in a pre-ileal position or posterior to the terminal ileum in a postileal position.