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Chapter 5
The abdomen
ANTERIOR ABDOMINAL WALL CHAPTER CONTENTS Anterior abdominal wall Stomach 154 Duodenum 159
Deep to the skin and subcutaneous fat of the lower anterior abdominal wall is a fibrous layer called Scarpa's fascia. This extends to the penis and scrotum (or labia majora) and fuses with the deep fascia of the perineum (Colles' fascia).
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Small intestine 162 lleocaecal valve 163 Appendix 164
Muscle layers
Large intestine 165 Liver 170 Biliary system 176 Pancreas 181 Spleen 185 Portal venous system 187 The kidneys 189 The ureter 194 The adrenal glands 196 The abdominal aorta 198 The inferior vena cava 199 Veins of the posterior abdominal wall
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The peritoneal spaces of the abdomen 202 Cross-sectional anatomy of the upper abdomen
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The external oblique muscle arises on the anterior surface of the lower ribs and is inserted into the linea alba, pubic crest, inguinal ligament and iliac crest. The internal oblique muscle arises from the lumbar fascia, the iliac crest and the lateral two-thirds of the inguinal ligament and is inserted into the linea alba and the costal margin. The transversus abdominis muscle arises from the lower ribs, interdigitating with the diaphragm, the lumbar fascia, the iliac crest and the lateral half of the inguinal ligament, and is inserted into the linea alba. The rectus abdominis muscle is a thick ribbon of muscle on either side of the midline from the costal cartilages to the pubic crest. It has three to four tendinous intersections at intervals along its length, which adhere to the anterior rectus sheath. The rectus sheath is formed by the aponeuroses of the other abdominal wall muscles as they surround the rectus muscle to attach to the linea alba. Umbilical ligaments The median umbilical ligament is the fibrous remnant of the urachus which runs from the fundus of the bladder on the deep surface of the anterior abdominal wall to the umbilicus as a cord of variable thickness. It is covered by a fold of peritoneum. The medial umbilical ligaments are the fibrous remnants of the obliterated umbilical arteries and run from the internal iliac artery (from the origin of the superior vesical branch on each side) to the umbilicus on the deep surface of the anterior abdominal wall. These are also covered by a fold of peritoneum.
