Distinguishing concepts: abdominal cavity, abdominopelvic cavity (abdominal cavity proper), and peritoneal cavity
Before studying the upper floor, it is necessary to distinguish three closely related concepts. Abdominal cavity is the space bounded from the inside by the endoabdominal fascia. When examining the anterior abdominal wall layer by layer, the following are consistently located: skin, subcutaneous adipose tissue, superficial and deep fasciae, muscle layers, endoabdominal fascia, properitoneal tissue, and parietal peritoneum.
Abdominal cavity proper is the space bounded by the parietal peritoneum; it is specifically where the upper and lower floors are distinguished. The slit-like space between the parietal and visceral peritoneum is called the peritoneal cavity. Between the posterior leaf of the parietal peritoneum and the endoabdominal fascia lies the retroperitoneal space.
Boundaries and contents of the upper floor
The upper floor of the abdominal cavity is located above the transverse colon and its mesentery, which serve as the boundary with the lower floor. It contains the liver with the gallbladder, the spleen, the stomach, part of the duodenum, as well as a system of compartmentalized spaces: the right and left hepatic bursae, the inferior hepatic bursa (subhepatic bursa), the pregastric bursa, and the omental bursa.
Ligaments of the liver and stomach
The ligaments of the liver are few: the round ligament of the liver represents the free edge of the falciform ligament; the coronary ligament at its edges passes into the right and left triangular ligaments.
The ligaments of the stomach are divided into superficial (running vertically) and deep (running horizontally).
- Superficial: gastrocolic ligament (upper part of the greater omentum), gastrosplenic ligament (contains short gastric arteries from the splenic artery), gastrophrenic ligament, phrenicooesophageal ligament, hepatogastric ligament, hepatoduodenal ligament (note: hepatoduodenal includes hepatoduodenal; hepatogastric and hepatopancreatic/etc. as applicable; sticking to standard translation: hepatogastric, hepatoduodenal).
- Deep (between the pancreas and stomach): gastropancreatic and retroduodenal/gastropancreatic folds/ligaments.
Hepatic and subhepatic bursae
The right hepatic bursa is located above the right lobe of the liver. It is bounded superiorly by the diaphragm, inferiorly by the right lobe of the liver, and to the left by the falciform ligament; inferiorly it communicates freely with the right lateral paracolic gutter and the subhepatic bursa.
The left hepatic bursa lies above the left lobe of the liver: to the right is the falciform ligament, to the left is the left triangular ligament, superiorly is the diaphragm; anteriorly it communicates with the pregastric bursa.
The subhepatic bursa is bounded superiorly and anteriorly by the inferior surface of the right lobe of the liver, inferiorly by the transverse colon and its mesentery, to the left by the porta hepatis, and communicates to the right with the right lateral paracolic gutter.
Lesser and greater omenta
The lesser omentum is formed by three consecutively arranged ligaments: the gastrophrenic, hepatogastric, and hepatoduodenal ligaments. The hepatoduodenal ligament contains the "portal triad": to the right is the common bile duct (formed by the common hepatic and cystic ducts), to the left is the proper hepatic artery, and posteriorly between them is the portal vein.
In systemic anatomy, the greater omentum is represented by ligaments extending from the diaphragm to the organs; in clinical anatomy, it refers to the gastrocolic ligament and the freely hanging lower section.
Pregastric bursa and splenic recess
The pregastric bursa is located anterior to the stomach. Walls: anterior — inferior surface of the left lobe of the liver; posterior — lesser omentum and anterior surface of the stomach; superior — liver and diaphragm. The bursa communicates with the subhepatic bursa and through it with the right lateral paracolic gutter, and along the path of the greater omentum with the lower floor of the abdominal cavity.
The lateral division of the pregastric bursa is represented by the splenic recess. Three ligaments are associated with the spleen: the true gastrosplenic and phrenicosplenic ligaments, as well as the phrenicocolic ligament extending from the splenic flexure of the transverse colon to the diaphragm. The latter separates the splenic recess from the left lateral paracolic gutter, so there is no communication between them.
Omental bursa and omental foramen
The omental bursa is the most difficult to access for surgical exploration. Its walls are:
- anterior — lesser omentum, posterior surface of the stomach, and part of the gastrocolic ligament;
- posterior — parietal peritoneum covering the pancreas, aorta, inferior vena cava, left kidney, adrenal gland, and nerve plexuses;
- superior — diaphragm and caudate lobe of the liver;
- inferior — transverse colon and its mesentery;
- left — spleen with its ligaments;
- right — no wall: the cavity transitions into the vestibule of the omental bursa and further into the omental foramen.
The bursa forms superior and anterior recesses; the superior recess is the most difficult to access for inspection.
Boundaries of the omental (Winslow's) foramen: anterior — hepatoduodenal ligament, posterior — parietal peritoneum (covering the inferior vena cava), superior — caudate lobe of the liver, inferior — duodenorenal ligament and the superior part of the duodenum.
Key points
- The abdominal cavity proper, abdominopelvic cavity, and peritoneal cavity differ in their fascial and serous boundaries.
- The transverse colon and its mesentery separate the upper floor of the abdominal cavity from the lower floor.
- The falciform ligament divides the right and left hepatic bursae; the subhepatic bursa communicates with the right lateral paracolic gutter.
- The lesser omentum consists of three ligaments; the hepatoduodenal ligament contains the common bile duct, hepatic artery, and portal vein.
- The pregastric bursa communicates with the subhepatic bursa and extends laterally into the splenic recess.
- The phrenicocolic ligament isolates the splenic recess from the left lateral paracolic gutter.
- The omental bursa lacks a right wall and communicates with the peritoneal cavity via the omental foramen.
- The boundaries of the omental foramen are a key landmark during operations on upper-floor organs.