Definition
The abdominal cavity, also called the abdominal cavity, begins below the diaphragm and extends to the level of the iliac crest. There, the abdominal cavity merges into the smaller pelvic cavity, which extends to the pelvic floor. The entire abdominal and pelvic cavity is lined by the peritoneum.
From the outside, the abdominal cavity is stabilised and protected by the abdominal muscles. The upper part is additionally surrounded by ribs. The abdominal cavity accommodates a large number of organs. In addition to the digestive organs, the spleen is also located in it.
Anatomy of the abdomen
The organs do not lie freely in the abdominal cavity, but are connected to the abdominal wall via the so-called mesentery. The mesentery is a peritoneal fold at the back of the abdominal wall through which blood vessels run to the individual organs. The organs in the abdominal cavity include the stomach, liver, gall bladder, pancreas, small and large intestine and spleen (the exact location of the organs is discussed below).
The kidneys are not located in the abdomen, but behind it, built into a fat capsule. The pelvic cavity contains the bladder and the internal genital organs, in men the prostate gland, in women the ovaries and the uterus. In addition to the organs, the abdominal cavity is also traversed by the large vessels (the aorta and the inferior vena cava), which supply the abdominal organs and then move on to the legs.
There is also fatty tissue in the abdominal cavity. The structure of the peritoneum, which is interspersed with a great deal of fatty tissue and is located in front of the small intestine, should be emphasized here. The upper right abdominal cavity is filled by the liver with the small gall bladder.
The gallbladder is almost completely covered by the liver. The liver can be imagined as a triangular structure with one leg going into the left abdomen and the other down. In some diseases, the liver can become so large that it fills a large space in the abdominal cavity and extends far into the lower right abdomen.
In the middle of the upper abdomen is the transition from the stomach to the duodenum, also called duodenum. Behind it lies the head of the pancreas. Bile from the gallbladder and pancreatic secretion reach the duodenum via two ducts.
This is particularly important for the digestion of fat. Below these organs, the colon moves once from the right to the left side. In the lower right abdominal cavity is the transition from small intestine to large intestine.
This is also where the appendix with its appendix is located, which causes pain in case of inflammation. In the upper left abdominal cavity there is first the stomach, which merges into the duodenum in the middle of the abdomen. Hidden behind the stomach is the pancreas, whose head is surrounded by the duodenum.
Its tail extends to the back left to the spleen. Besides digestive secretions, the pancreas produces insulin, which is necessary for a stable blood sugar level. The spleen is hidden in the spleen cavity, which is protected deep in the back by the ribs.
If the ribs are broken, however, it can be injured by them, which can lead to a rupture of the spleen and internal bleeding. Below the spleen is the kidney with adrenal gland embedded in its fat capsule. In the lower abdomen, as on the right, there is the large and small intestine.
The small intestine is 5-6 meters long and takes up a lot of space. It is surrounded by the large intestine like a frame. It begins in the right lower abdomen and moves into the pelvic cavity in the left lower abdomen, where it merges into the rectum.
The lymphatic system, a fluid system parallel to the blood vessels, serves especially for the body’s immune defence. The filtered, excess tissue fluid is filtered and channelled through several large and small lymph nodes to the large veins in the upper chest area. In the abdominal cavity, the lymph nodes can be divided into superficial and deep lymph nodes, with the former leading into the deeper ones.
By definition, the superficial lymph nodes do not belong directly to the abdominal cavity. The deep lymph nodes follow the course of the abdominal aorta, the largest artery in the abdomen. From most of the abdominal organs, with the exception of the descending colon, the lymph first flows into a trunk of the internal organs and is collected there and sent on to the lymph drainage of the upper body.
On the way there are the abdominal lymph nodes and the crumb lymph nodes. The lower organs drain the lymph via the inguinal lymph nodes. These also lead to the lymphatic system of the upper body. For each organ, a so-called sentinel lymph node can be named, which is the first lymph node to be affected in the case of spreading carcinomas. This is always removed during tumour operations and pathologically examined.
All articles in this series: