To understand the shape and form of peritoneum in a better way, it is good to have a look at it at different planes. This will make understanding of the arrangement of the layers of peritoneum easy.
Peritoneum at the level of fourth lumbar vertebra:
The parietal peritoneum lining the anterior abdominal wall below the umbilicus is smooth, except from the low ridges produced by the median umbilical ligament and the lateral umbilical ligaments.
The median umbilical ligament extends from the apex of the urinary bladder to the umbilicus. It represents the urachus, the remains of the fetal allontois. The lateral umbilical ligaments represent the obliterated umbilical arteries passing from the internal iliac arteries to the umbilicus.
The parietal peritoneum passes onto the posterior abdominal wall and becomes continuous with the visceral peritoneum covering the ascending and descending colon. Near the center, in the region of the aorta and inferior vena cava, the parietal peritoneum becomes continuous with the mesentery of the small intestine.
It should be kept in mind that the peritoneum forms a continuous layer and can be traced around the entire abdominal cavity without interruption.
Peritoneum at the level of twelfth thoracic vertebra:
At the level of twelfth thoracic vertebra, the parietal peritoneum lining the anterior abdominal wall forms a sickle shaped fold called the falciform ligament. This ligament connects the anterior surface of the liver to the anterior abdominal wall and diaphragm. There is a free border of the ligament where the two layers of peritoneum are continuous with one another. The ligamentum teres (the obliterated umbilical vein of the fetus which passes upward to enter the groove between the quadrate lobe and left lobe of the liver) lies in this free border.
At the level of the twelfth thoracic vertebra, a few important structures of the peritoneum exist. If the parietal peritoneum is followed on the left side, it reaches the lateral margin of the left kidney. It becomes continuous with the visceral peritoneum covering the kidney, which then leaves the kidney and passes to the hilum of the spleen as the Splenicorenal ligament (also known as lienorenal ligament). The peritoneum then covers the spleen and reaches the hilum again to be reflected onto the greater curvature of stomach as the anterior layer of the gastrosplenic omentum. The visceral layer of peritoneum then covers the anterior surface of stomach and leaves the lesser curvature to form the anterior layer of the lesser omentum. On the right, the lesser omentum has a free border where the peritoneum folds around the bile duct, hepatic artery and portal vein to form the anterior margin of the epiploic foramen.
The peritoneum then forms the posterior layer of the lesser omentum and becomes continuous with the visceral layer of peritoneum covering the posterior wall of the stomach. At the greater curvature of the stomach, the peritoneum leaves the stomach as the posterior layer of gastrosplenic omentum and reaches the hilum of the spleen. Here it is reflected backward to the posterior abdominal wall, forming the anterior layer of the splenicorenal ligament. The peritoneum now covers the anterior surface of the pancreas, aorta and the inferior vena cava forming the posterior wall of the lesser sac. The peritoneum passes onto the anterior surface of the right kidney and sweeps around the lateral abdominal wall to reach the anterior abdominal wall.
Thus the peritoneum forms one continuous layer around the abdomen.
Peritoneum as seen on the sagittal section of the abdomen and pelvis:
The parietal peritoneum lining the anterior abdominal wall can be traced upward to the left of the falciform ligament to reach the undersurface of the diaphragm. Here it is reflected onto the upper surface of the liver as the anterior layer of left triangular ligament. The visceral peritoneum then covers the anterior and inferior surfaces of the liver until it reaches the porta hepatis. Here the peritoneum passes to the lesser curvature of the stomach as the anterior layer of the lesser omentum. Having covered the anterior surface of the stomach, the peritoneum leaves the greater curvature, forming the anterior layer of the greater omentum. The greater omentum hangs down as a fold in front of the coils of intestine and contains within it the lower part of the lesser sac. Having reached the lowest limit of the greater omentum, the peritoneum folds upward and forms the posterior layer of the greater omentum. On reaching the inferior border of the transverse colon, the peritoneum covers its posterior surface and then leaves the colon to form the posterior layer of the transverse meoscolon. The peritoneum then passes to the anterior border of pancreas and runs downward anterior to the third part of the duodenum.
The peritoneum now leaves the posterior abdominal wall as the anterior layer of the mesentery of the small intestine. The visceral peritoneum covers the anterior surface of the upper part of the rectum. From here it is reflected onto the posterior surface of the upper part of the vagina, forming the important rectouterine pouch. In the males, the peritoneum is reflected onto the upper part of the urinary bladder to form the rectovesical pouch. In both sexes the peritoneum passes from the bladder to the anterior abdominal wall.