Abdomen: Topographic Anatomy

The abdomen is part of the body, located between the chest at the top and the pelvis below. The upper border of the abdomen passes from the base of the xiphoid process along the costal arches to the XII thoracic vertebra. On the lateral side, the abdominal boundaries are determined from the back axillary line from the costal arch at the top to the iliac crest at the bottom. The lower border of the abdomen on the right and left forms the anterior segment of the iliac crest and the line conventionally held at the level of inguinal folds from the superior anterior iliac spine to the pubic tubercle. This is the outer border of the abdomen. They do not coincide with the boundaries of the abdominal cavity, which at the top (cranial) extends to the dome of the diaphragm (level IV of the rib), and below reaches the bottom of the pelvic cavity.

In order to more accurately determine the location of the organs in the abdominal cavity, their topography and projection onto the outer covers of the abdomen are divided by two horizontal lines into three floors. One line passes between the cartilages of the X ribs - the intercostal line (lmea bicostarum). The other line connects the superior anterior striae of the iliac bones - the interaesthetic line (linea bispinatum). Thus, above the intercostal line is the upper floor - the epigastrium. Between the intercostal and interstitial lines is the middle floor - the mesogastrium, and below the interstitial line is the hypogdstrium. In addition, two vertical lines along the lateral edges of the rectus abdominal muscles from the costal arch to the pubic tubercle, each of these floors is divided into three separate areas. Accordingly, the right and left subcostal regions (regiones hypochondricae dextra and sinistra) and epigastric region (regio epigastrica) are distinguished in the epigastrium. The right and left lateral regions (regiones laterales dextra et sinistra) are distinguished in the forehead , and between them is the umbilical region (regio umbilicalis). In the hypogastrium, the right and left inguinal regions (regiones inguinales dextra et sinistra) and the pubic region (regio pubica) are distinguished.

The internal organs located in the abdominal cavity are projected onto the anterior abdominal wall. In the actual epigastric region, the stomach, the duodenum, the left lobe of the liver, the pancreas are projected. The right side of the liver corresponds to the right hypochondrium with the gallbladder, the upper pole of the right kidney and the right adrenal gland, the right (hepatic) bend of the colon. In the region of the left hypochondrium, the spleen, the bottom of the stomach, the left (splenic) bend of the colon, the upper pole of the left kidney and the left adrenal gland, the tail of the pancreas are projected.

In the umbilical region there is a large curvature of the stomach, the lower horizontal and ascending parts of the duodenum, the mesenteric ligament of the small intestine, the transverse colon, the portal of the kidneys, the ureters. In the right lateral region there are a part of the loops of the small (ileum) intestine, the ascending colon, the lower pole of the right kidney. In the left lateral region, a part of the loops of the small (jejunum) gut, the descending colon, the lower pole of the left kidney are determined.

In the pubic region, the bladder (filled) and the lower parts of the ureters, the uterus with uterine tubes (in women), a part of the loops of the small intestine are projected. In the right inguinal region are the terminal section of the small (ileum) gut, the cecum, the appendix, the right ureter; in the left inguinal region - part of the loops of the small intestine, sigmoid colon, left ureter.

The skin in the abdominal wall is thin, easily folded. The scalp in men (in the pubis area) rises up to the navel, and sometimes to the front surface of the sternum. In women, the hairline is only in the pubic region, the top line of the hair is horizontal. Subcutaneous fat is more developed in the lower part of the abdominal wall.

The anterior and lateral walls of the abdominal cavity are formed by three pairs of broad abdominal muscles, their tendon stretches and rectus abdominal muscles with their fascia. Muscles and fasciae of the abdominal walls form the abdominal press, which protects the internal organs from external influences, exerts pressure on them and holds them in a certain position, and also participates in the movements of the spine and ribs. The structure of the back wall of the abdominal cavity includes the lumbar spine, as well as paired large lumbar and square muscles of the waist. The lower wall is formed by ileal bones, muscles and fascia of the pelvic floor - the pelvic diaphragm and urogenital diaphragm.

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