caecum

Cecum: It is the thickest, shortest and most accessible part of the large intestine.

1, peripheral relation

There are indirect cavities around (sometimes mesangium appears on the posterior medial side), and the anterior abdominal wall is in front; Followed by the posterior abdominal wall and iliopsoas muscle; Inside are ileum and mesenteric sinus; Outside is the lateral sulcus of colon; Ascending colon; Lower pelvis.

2. Internal relations

There are three channels, namely ileum, colon and appendix. Three colonic bands (omentum band, mesangial band and independent band) on its surface are concentrated in the root of appendix.

Cecum The cecum is the starting point of the large intestine, the lower end is the enlarged blind end, and the left side is connected with the end of the ileum, which is bounded by ileocecal flap, ascending colon and ileum. Ileocecal valve is an upper and lower half-moon valve formed by the end of ileum protruding into cecum. The function of this flap is to prevent the contents of small intestine from flowing into large intestine too quickly, so that food can be fully absorbed in small intestine and the contents of cecum can be prevented from flowing back to ileum. The cecum is located in the right iliac fossa, the high cecum can be above the iliac fossa or even below the right lobe of the liver, and the low cecum can reach the small pelvis.

appendix

The appendix, a worm-like appendix, is a degenerate organ of human beings (the appendix of herbivores is very developed). It is about 7-9 cm long and 0.5 cm in diameter. Located in the lower right of the abdomen, in the cecum, the proximal end communicates with the cecum, and the distal end is locked. Because the appendix cavity is small and blind. Food residues and fecal stones can easily fall into the lumen, blocking the lumen and causing inflammation. Body surface projection is called Maxwell's point, which is located at the junction of the outer, middle 1/3 of the line from the right anterior superior iliac spine to the umbilical cord. There is tenderness at this point in appendicitis.

The appendix of adults is mainly related to immune function. Shortly after birth, lymphoid tissue began to accumulate in the appendix, reaching a peak around the age of 20, and then rapidly declined and disappeared after the age of 60. However, in the stage of physical development, the appendix can play the role of a lymphoid organ, promoting the maturation of B lymphocytes (a kind of white blood cells) and the production of immunoglobulin A antibodies. Researchers have also proved that molecules involved in appendix formation help lymphocytes to migrate to other parts of the body.

From this point of view, it seems that the function of the appendix is to expose white blood cells to a large number of antigens in the gastrointestinal tract, that is, foreign bodies. Therefore, the appendix can help inhibit the potentially destructive humoral antibody response and provide local immunity. The appendix absorbs antigens in the intestine and reacts to them. This local immune system plays an important role in physiological immune response and control of food, drugs, bacteria or virus antigens. At present, scientists are studying the relationship between these local immune responses and inflammatory bowel disease and autoimmune reactions.