What Is the Jejunum?
Jejunum: The part of the mammalian small intestine after the duodenum. Although it can be further separated, the anterior segment is the jejunum and the posterior segment is the ileum, but there is no clear boundary between the two. The human jejunum is located on the upper left side of the abdominal cavity, and the ileum is on the lower right side. The jejunum is slightly thicker and slightly reddish due to the distribution of many blood vessels. The jejunum begins at the duodenal jejunum and occupies 2/5 of the full length of the jejunum and the upper left part of the abdominal cavity. The ileum occupies the distal 3/5 of the full length of the jejunum and continues the cecum in the right popliteal fossa. The ileum is located in the lower right part of the abdominal cavity and part of it is located in the pelvic cavity.
- Chinese name
- jejunum
- Foreign name
- intestinum jejunum
- Nature
- After the small intestine duodenum of mammals
- Belongs to
- The small intestine is located in the abdomen, with the upper end connecting the pylorus and stomach
- Jejunum: The part of the mammalian small intestine after the duodenum. Although it can be further separated, the anterior segment is the jejunum and the posterior segment is the ileum, but there is no clear boundary between the two. The human jejunum is located on the upper left side of the abdominal cavity, and the ileum is on the lower right side. The jejunum is slightly thicker and slightly reddish due to the distribution of many blood vessels. The jejunum begins at the duodenal jejunum and occupies 2/5 of the full length of the jejunum and the upper left part of the abdominal cavity. The ileum occupies the distal 3/5 of the full length of the jejunum and continues the cecum in the right popliteal fossa. The ileum is located in the lower right part of the abdominal cavity and part of it is located in the pelvic cavity.
Structure of jejunum and jejunum
- Both the jejunum and ileum are connected to the posterior abdominal wall by the mesentery and have greater mobility. The mucosa of the jejunum and ileum forms many ring-shaped ridges, and there are a large number of small intestinal villi on the ridges, which greatly increases the absorption area of the small intestine. The ring-shaped salamander has the highest density in the upper 1/3 segment of the jejunum, and gradually decreases downward to become smaller, and disappears to the lower part of the ileum. The mucosal layer contains lymphoid follicles, which are divided into two types: isolated lymphoid follicles and aggregated lymphoid follicles. The former is dispersed in the jejunum and ileal mucosa, and the latter is more common in the lower part of the ileum. Consistent with the long axis of the small intestine, often located at the mesangial border of the ileum. Intestinal typhoid disease occurs in the collection of lymphoid follicles, which can be complicated by intestinal perforation or intestinal bleeding.
- The jejunum and ileum circle in the abdominal cavity to form an intestine. There is no clear boundary between the jejunum and ileum, but in appearance, the diameter of the jejunum is thicker, the wall is thicker, there are more blood vessels, and the color is red; while the diameter of the ileum is thinner, the wall is thinner, and there are fewer blood vessels , The color is lighter. In addition, the thickness of the mesentery gradually increases from top to bottom, and the fat content is increasing. The distribution of blood vessels in the mesentery of the jejunum and ileum is also different. The straight blood vessels of the jejunum are longer than those of the ileum.
- On the ileal wall ranging from 0.3 to 1 m from the end of the ileum, about 2% of adults have protrusions of 2-5 cm in length, protruding outward from the intestinal wall and slightly smaller than the ileum. It is called Meckel diverticulum. This is the embryonic yolk pedicle that has not disappeared. Forming. This diverticulum may be inflamed or with ulcer perforation. Because it is located close to the appendix, the symptoms are similar to appendicitis.