Corpus: Abdomen

In anatomy, the abdomen refers to the belly, which is made up of the abdominal wall, abdominal cavity (cavitas abdominalis) and abdominal viscera.

Together with the thorax and the pelvis, the abdomen forms the trunk.

2.1. Borders

The upper edge of the abdomen is formed by the lowest ribs and the tip of the breastbone (sternum). The lower edge is marked by the bony upper edge of the pelvis and the inguinal ligament. The anterior and lateral borders of the abdomen are formed by the abdominal muscles and the subcutaneous tissue lying on them with the abdominal skin stretched over them.

2.2. Surface

The surface aspect of the abdomen depends on the nutritional and training status. In obese people, the abdomen is convex overall thanks to a pronounced layer of fat and has no other anatomical features apart from the navel (umbilicus) located in the median line. In lean and fit people, on the other hand, the relief of the abdominal muscles is visible, especially the indentations of the rectus abdominis muscle caused by the 3 intersectiones tendineae.

2.3. Topography

The abdomen can be divided topographically into three sections and 6 anatomical regions.

2.3.1. Upper abdomen

The upper abdomen or epigastrium is the abdominal area above the navel, enclosed by ribs: it included the following regions:

• Regio epigastrica
• Regio hypochondriaca

2.3.2. Midline abdomen

The middle abdomen or mesogastrium is the free central area around the belly button, which has the approximate shape of a narrow corset. It consists of:

• Regio umbilicalis
• Regio lateralis

2.3.3. Lower abdomen

The lower abdomen or hypogastrium is the abdominal area enclosed by the pelvis "below" the navel. In lay medicine, it is also referred to as the abdomen. It can be further subdivided into the following anatomical regions:

• Regio pubica
• Regio inguinalis

2.4. Abdominal cavity

The abdominal cavity (cavitas abdominalis) is a large body cavity in the abdominal region that houses the abdominal organs. It is enclosed by the abdominal walls, borders cranially on the diaphragm and merges caudally into the pelvic cavity.

2.5. Abdominal viscera

The most important part of the abdomen are the abdominal organs contained within it. In principle, the organs within the abdomen are divided into intraperitoneal and extraperitoneal abdominal tissues according to the type of their peritoneal covering. The abdominal viscera include

• Stomach (gaster)
• Small intestine (intestinum tenue)
• Large intestine (intestinum crassum)
• Liver (hepar)
• Gall bladder (Vesica fellea)
• Pancreas (pancreas)
• Kidneys (Renes)
• Adrenal glands (Glandulae suprarenales)
• Ureter (ureter)
• Spleen (splen)

Examination of the abdomen is an important part of the clinical diagnosis. It consists primarily of inspection, auscultation, percussion and palpation. In addition to these simple examination procedures, a comprehensive range of diagnostic equipment is available. This includes, among other things:

• Sonography (abdominal sonography)
• X-ray (abdominal overview)
• Computed tomography (abdominal CT)
• Magnetic resonance imaging (abdominal MRI)